- NEW: Officials revise total number of girls kidnapped to at least 230
- This poor corner of Nigeria is no stranger to such brazen, violent acts
- Boko Haram-related violence killed 1,500 in the first three months of 2014
- The latest incident has ratcheted up pressure on the military
Abuja, Nigeria (CNN) -- The heavily armed militants stormed the girls dormitory in the middle of the night, herding more than 200 students on to vehicles and burning down nearby buildings as they made their escape.
That was a week ago Monday.
Of the 230 students abducted from the Government Girls Secondary School in the Nigerian town of Chibok, about 190 are still missing, one official said.
The number of girls taken from the school has been revised by officials several times, and on Monday, CNN spoke with Principal Asabe Kwambura, who said a new figure of at least 230 was determined after reviewing records and taking reports from parents.
Isa Umar Gusau, a spokesman for the Borno provincial governor's office, put the number at 234 -- 129 science students and 105 art students.
He said in a written statement that the confusion resulted because the art students didn't leave campus as expected on the day of the attack. The head of the dormitory initially didn't count them among the missing.
Seven girls escape Nigerian militants 
A video of Abubakar Shekau, who claims to be the leader of the Nigerian Islamist extremist group Boko Haram, is shown on September 25, 2013. Boko Haram is an Islamist militant group waging a campaign of violence in northern Nigeria. The group's ambitions range from the stricter enforcement of Sharia law to the total destruction of the Nigerian state and its government. Click through to see recent bloody incidents in this strife-torn West African nation: 
Bodies lie in the streets in Maiduguri after religious clashes in northern Nigeria, on July 31, 2009. Boko Haram exploded onto the national scene in 2009 when 700 people were killed in widespread clashes across the north between the group and the Nigerian military. 
An unidentified official displays burned equipment inside a prison in Bauchi on September 9, 2010, after the prison was attacked by suspected members of Boko Haram on September 7. About 720 inmates escaped during the prison break, and police suspect the prison was attacked because it was holding 80 members of the sect. 
Nigerian President Goodluck Jonathan, second from left, stands on the back of a vehicle after being sworn-in as President during a ceremony in the capital of Abuja on May 29, 2011. In December 2011, Jonathan declared a state of emergency in parts of the country afflicted by violence from the militant Islamist group. 
Rescue workers evacuate a wounded person from a U.N. building in Abuja on August 26, 2011. The building was rocked by a bomb that killed at least 23 people, leaving others trapped and causing heavy damage. Boko Haram had claimed responsibility for the attack in which a Honda packed with explosives rammed into the U.N. building, shattering windows and setting the place afire. 
A photo taken on November 6, 2011, shows state police headquarters burned by a series of bomb and gun attacks that targeted police stations, mosques and churches in Damaturu on November 4, 2011. Attackers left scores injured -- probably more than 100 -- in a three-hour rampage in the Yobe state city of Damaturu. Sixty-three people died. 
Men look at the wreckage of a car after a bomb blast at St. Theresa Catholic Church outside Abuja on December 25, 2011. A string of bombs struck churches in five Nigerian cities, leaving dozens dead and wounded on the Christmas holiday, authorities and witnesses said. Boko Haram's targets included police outposts and churches as well as places associated with "Western influence." 
A paramedic helps a young man injured during one of the multiple explosions and shooting attacks as he leaves a hospital in the northern city of Kano on January 21, 2012. A spate of bombings and shootings left more than 200 people dead in Nigeria's second-largest city. Three days later, a joint military task force in Nigeria arrested 158 suspected members of Boko Haram. 
A photo taken on June 18, 2012, shows a car vandalized after three church bombings and retaliatory attacks in northern Nigeria killed at least 50 people on June 17 and injured more than 130 others, the Nigerian Red Cross Society said. 
A French family kidnapped on February 19, 2013, in northern Cameroon is released after two months in captivity in Nigeria. The family of four children, their parents and an uncle were kidnapped in Waza National Park in northern Cameroon, situated near the border with Nigeria. One of the captive men read a statement demanding that Nigeria and Cameroon free jailed members of Boko Haram. 
A soldier stands in front of a damaged wall and the body of a prison officer killed during an attack on a prison in the northeastern town of Bama on May 7, 2013. Two soldiers were killed during coordinated attacks on multiple targets. Nigeria's military says more than 100 Boko Haram militants carried out the attack. 
A deserted student hostel on August 6, 2013, is shown after gunmen stormed a school in Yobe state, killing 20 students and a teacher, state media reported on July 6, 2013. Boko Haram regularly carries out attacks in Yobe, in Nigeria's northeast. 
A photograph made available by the Nigerian army on August 13, 2013, shows improvised explosive devices, bomb making materials and detonators seized from a Boko Haram hideout. Gunmen attacked a mosque in Nigeria with automatic weapons on August 11, 2013, killing at least 44 people. 
Nigerian students from Jos Polytechnic walk on campus in Jos, Nigeria, on September 30, 2013. Under the cover of darkness, gunmen approached a college dormitory in a rural Nigerian town and opened fire on students who were sleeping. At least 40 students died, according to the News Agency of Nigeria. 
Soldiers stand outside the 79 Composite Group Air Force base that was attacked earlier in Maiduguri on December 2, 2013. Hundreds of Boko Haram militants attacked an Air Force base and a military checkpoint, according to government officials. 
Former hostage and French Catholic Priest Georges Vandenbeusch speaks to reporters outside Paris, France, on January 1, after his release. Vandenbeusch was snatched from his parish church in Cameroon on November 13, 2013. Boko Haram claimed responsibility for kidnapping the priest. 
A man receives treatment at Konduga specialist hospital after a gruesome attack on January 26. It's suspected that Boko Haram militants opened fire on a village market and torched homes in the village of Kawuri in Borno state, killing at least 45 people. 
Police officers stand guard in front of the burned remains of homes and businesses in the village of Konduga, in northeastern Nigeria, on February 12. Suspected Boko Haram militants torched houses in the village, killing at least 23 people, according to the governor of Borno state on February 11. 
Ibrahim Gaidam, governor of Yobe state, left, looks at the bodies of students inside an ambulance outside a mosque in Damaturu. At least 29 students died in an attack on a federal college in Buni Yadi, near the the capital of Yobe state, Nigeria's military said on February 26. Authorities suspect Boko Haram carried out the assault in which several buildings were also torched. In April as many as 200 girls were abducted from their boarding school in northeastern Nigeria by heavily armed Boko Haram Islamists who arrived in trucks, vans and buses, officials and witnesses said. The group has recently stepped up attacks in the region, and its leader released a video last month threatening to kidnap girls from schools. 
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Boko Haram: Nigeria's crisis 
Fate of kidnapped students uncertain 
Nigerian officials: 200 girls abducted 
Boko Haram 'increasingly monstrous' No one knows where the missing girls are. And even more surprising, no one's particularly shocked.
"All the community are sympathizing with the parents," Kwambura told CNN earlier. But, she said, "the people in the villages are not surprised."
Such is life in the lawless Borno province.
Tucked away near the border with Cameroon, with phone services cut off and travel strongly discouraged, this poor corner of Nigeria is no stranger to such brazen, violent acts.
For 11 months, the provinces of Borno, Yobe and Adamawa have been under a state of emergency due to relentless assaults blamed on Boko Haram.
The Islamist militant group has bombed churches and mosques; kidnapped women and children; and assassinated politicians and religious leaders.
Boko Haram -- whose name means "Western education is sin" in the local Hausa language -- says it wants to impose a stricter enforcement of Sharia law across Africa's most populous nation.
The group has gone about its misguided mission with such depressing regularity that residents have become somewhat numb.
Where's the president?
Nigerians marvel that U.S. President Barack Obama traveled to Massachusetts after the Boston Marathon bombings that killed three people last year.
Boko Haram-related violence killed 1,500 in the first three months of this year alone. And yet, Nigerian President Goodluck Jonathan has not visited the region recently.
Explosion kills dozens in Nigeria 
Up to 200 girls kidnapped by terrorists 
Abubakar Shekau is the leader of Boko Haram in Nigeria. A reward up to $7 million has been offered by the U.S. government. 
Mullah Mohammed Omar is the spiritual leader of the Taliban. A reward of up to $10 million has been offered by the U.S. government. 
Abu Bakr al-Baghdadi is the leader of Islamic State in Iraq. A reward up to $10 million has been offered by the U.S. government. 
Ahmed Abdi Godane, also known as Mukhtar Abu Zubayr, is the leader of Al-Shabaab. A reward up to $7 million has been offered by the U.S. government. 
Nasir al Wuhayshi is leader of al Qaeda in the Arabian Peninsula. 
Hakimullah Mehsud is the leader of Tehrik-e-Taliban in Pakistan. A reward of up to $5 million has been offered by the U.S. government. Leaders of deadliest terrorist groups Part of it may have to do with geographic divisions.
Jonathan is from the predominantly Christian south. That's not just geographically distant but also culturally different from the Muslim-dominated, violence-wracked north.
To put things in perspective, none of Jonathan's major political rivals from the north attended his inauguration in 2011. And widespread violence broke out in the north when his presidential win was announced, with some residents claiming the election was rigged.
It's the opposite of what happened with Jonathan's predecessor.
The previous president, Umaru Yar'Adua, was from the north. During his tenure, violence ravaged the country's oil-rich, southern Niger Delta, with militant groups saying they wanted a fairer distribution of the region's oil wealth.
Where's the military?
The Nigerian military has been engaged in a brutal, ever-escalating fight with Boko Haram. Rights group accuse both sides of ruthlessness -- Boko Haram of indiscriminate attacks, and the military of extrajudicial killings.
But when it comes to the abductions of girls -- and there have been many -- the military has had a difficult time.
Last week, the defense ministry erroneously reported that all but eight of the girls from the latest kidnapping were free. It retracted a day later.
Lawan Zanna, the father of one of the students, said the government turned from using "blatant propaganda" to making a "blatant lie."
Part of the reason the military is loath to respond mightily may be because the girls who are kidnapped are raped, forced into servitude -- but rarely killed.
In February, 29 college students in the northern Yobe province were killed after an attack authorities blamed on Boko Haram. All of them were males. The women were spared.
In other instances, kidnapped girls were later rescued while working on farms. Many were pregnant or had babies -- the result of rape.
The spate of kidnappings began in May 2013 when Boko Haram leader Abubakar Shekau announced in a video that this was part of its latest bloody campaign. The kidnappings, he said, were retaliation for Nigerian security forces nabbing the wives and children of group members.
Those kidnapped, he said, would begin a new life as a "servant."
But the latest incident has ratcheted up the pressure on the military.
The military said "ongoing, frantic efforts" of security forces, vigilante groups and hunters are attempting to find and free the students.
But a week later, the fate of 190 girls remain unknown.
READ: Boko Haram: A bloody insurgency, a growing challenge
READ: A year of attacks linked to Nigeria's Boko Haram
CNN's Vladimir Duthiers reported from Abuja, and CNN's Holly Yan reported and wrote from Atlanta. CNN's Jonathan Mann, Faith Karimi, Nana Karikari-Apau and Chelsea J. Carter contributed to this report.
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