Legoland, Camp Pendleton affected

A helicopter flies over burning vegetation near homes in Carlsbad, California, on Wednesday, May 14. A couple of wildfires have forced evacuations in San Diego County after a high-pressure system brought unseasonable heat and gusty winds to the parched state.

A firefighter puts water on a smoldering fence outside a home in Carlsbad on May 14. The wildfire in Carlsbad is about 20 miles away from a wildfire in San Diego that has burned more than 1,500 acres.

A woman is escorted to safety May 14 in Carlsbad.

A firefighter sprays water onto a fully engulfed home in Carlsbad on May 14.

A Carlsbad police officer turns traffic away as flames rage behind him on May 14.

A wildfire approaches buildings in Carlsbad on May 14.

A helicopter drops water near the Rancho Santa Fe neighborhood of San Diego on Tuesday, May 13.

Trees burn on May 13 as the San Diego wildfire moves through a canyon between Rancho Santa Fe and the Fairbanks Ranch area.

A wildfire threatens luxury homes in the Fairbanks Ranch area on May 13.

Firefighters prepare to take on the wildfire in San Diego.

A helicopter battles the San Diego wildfire on May 13.

Firefighters arrive to assist local personnel in San Diego on May 13.

Smoke rises from a canyon where the San Diego wildfire burned on May 13.

Firefighters watch from a ridge as a helicopter drops retardant on the San Diego flames on May 13.

Billowing smoke rises as firefighters trek up the hills to battle the San Diego fire on May 13.

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• NEW: "Everyone was panicking and wanting to get out of there," Carlsbad worker says


• Emergency proclamation allows San Diego to access federal, state resources


• At least five fires are burning, county says


• Parts of Camp Pendleton, a Marine base, are evacuated

Carlsbad, California (CNN) -- Southern California firefighters were fighting five wildfires Wednesday in and around San Diego, prompting at least 15,000 evacuation notices to residents, businesses, schools and parts of a Marine Corps installation.

San Diego County proclaimed a local emergency Wednesday afternoon due to "at least five wildland fires burning," the county said. At least 20 structures were destroyed. The emergency allows the county to more easily access state and federal resources.

Statewide drought, hot, dry Santa Ana winds, low humidity and 90-degree-plus temperatures conspired to quintuple the number of wildfires Wednesday, which began with 350 firefighters fighting a 1,500-acre wildfire in San Diego.

But by noon, a second fire had erupted 20 miles away in Carlsbad, burning 100 acres and prompting the evacuation of thousands of people and a resort.

Then, a third ignited on Camp Pendleton, a training base, where a 150-acre fire led to the evacuations of the military's O'Neill Heights Housing, the De Luz Child Development Center and Mary Fay Pendleton Elementary School, the Marines said.

Another fire burned in the community of Fallbrook, adjacent to the military base. Camp Pendleton is the West Coast boot camp for enlistees.

The ferocious fires made for sensational, disturbing viewing.

"Oh, my God! Oh, my gosh!" California resident Kristin Michalec said on a video she shared with CNN as she drove through raging flames in Carlsbad, near where she lives.

"It was so hard to see because of the thick smoke," she later told CNN in an interview.

Jay Ringgold, an information technology manager in Carlsbad, smelled the smoke easily. Santa Ana winds, also called devil winds, whipped up the fires.

"People were very surprised that it came that close to the business district. There are a lot of big companies there -- near that is a brush area and homes," Ringgold said. "Everyone was panicking and wanting to get out of there."

San Diego fire officials were trying to spare some of their crews to assist Carlsbad, where a 100-acre wildfire prompted a mandatory evacuation.

"We're trying to free resources to send to Carlsbad, which also has a serious fire going on and is just across the freeway," said San Diego Fire Department spokesman Lee Swanson.

"Humidity is 3 to 4%, and it's about 100 degrees," he added.

Carlsbad officials said Wednesday afternoon that "mandatory evacuations are in progress" in that city's so-called Poinsettia Fire.

San Diego County said more than 11,000 residents, businesses and cell phones in Carlsbad were notified to evacuate, but an exact number wasn't immediately available, the county said on Twitter.

The Poinsettia Fire also prompted the evacuation of amusement park rides at Legoland in Carlsbad, the resort said on its Facebook page. Carlsbad officials said they alone issued 15,000 evacuation notices, including to three schools. Two unidentified structures were destroyed, city officials said.

Firefighters were igniting backfires in hills as a preventive measure against the wildfire and any possible advances on a residential neighborhood.

"This is extreme. This has gone from dry conditions to volatile conditions," said a Carlsbad firefighter after using a torch to ignite backfire. "This isn't something we don't normally see until November or September."

Back at the San Diego fire, authorities were concerned that the Santa Ana winds would set back their efforts since Tuesday morning to contain the wildfire, which improved overnight to 25% from 5%, said Cal Fire incident commander Ray Chaney.

The fire has burned 1,584 acres and prompted an evacuation Tuesday of 5,000 homes in San Diego and selected areas, authorities said. By Tuesday night, those residents had an "orderly return" to their homes, San Diego Police Chief Shelley Zimmerman said.

As of Wednesday morning, no structures had been damaged, and only two minor injuries -- for smoke exposure and heat-related illness -- had been reported, Chaney said.

In addition to the Santa Ana winds, 350 firefighters were expecting single-digit humidity, Chaney said.

"It does put us on edge," Chaney said of the forecast. "The weather is a very big concern for us."

Added Rancho Santa Fe Fire Department Chief Tony Michel: "The winds are going to be a problem."

"The battle isn't over," said San Diego Mayor Kevin L. Faulconer. "We have had crews out there that have worked all night."

Firefighting on early Wednesday focused on "mop-up operations," Chaney said.

The cause of the blaze, called the Bernardo Fire, is still under investigation, he said.

The National Weather Service issued a red flag warning for areas around San Diego through 8 p.m. Wednesday. As the agency noted, "a red flag warning means that critical fire weather conditions are either occurring now or will shortly," with strong winds, low humidity and warm temperatures feeding into "extreme fire behavior."

Temperatures in the southern California city are forecast to peak in the mid-90s Wednesday and Thursday with no sign of rain, before cooling somewhat later in the week.

What to know about wildfires

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CNN's Ed Payne, Karan Olson, Greg Botelho and Matthew Stucker contributed to this report. Paul Vercammen reported from Carlsbad.