Police hunt attacker at university

• Four victims say they were attacked from behind by a white male, police say


• In several cases, the victims fought back and bystanders got involved


• None of the women was sexually assaulted, police spokesman says

(CNN) -- Law enforcement officials in Gainesville, Florida, say they are investigating attempted sexual assaults on women near and on the University of Florida campus.

There have been at least four attacks, each that has similar characteristics, said Officer Ben Tobias, a spokesman for the Gainesville Police Department, on Monday.

The victims are all in their early 20s and white and describe a white male attacking them from behind. None of the victims has been able to describe her attacker in enough detail to create a composite sketch, police said.

City and campus police are working together to find a man who appears in surveillance videos, but Tobias said police have not named anyone as a suspect.

Local authorities are working with state investigators on possible DNA testing from clothing, he said.

None of the victims was sexually assaulted, Tobias noted. He praised victims for fighting back and bystanders for getting involved when they heard something suspicious.

Around 9:30 p.m. August 30, a 21-year-old woman was approached from the back, punched in the head and pulled into hedges near an apartment complex, said Tobias. The attacker tore at her clothing and ripped off her underwear, he said. The assailant was wearing a shirt with the university mascot, a gator, the police spokesman said.

A homeowner who heard the two struggling went outside and approached, causing the attacker to run away, he said.

Just before 1 a.m. August 31, a 20-year-old woman was walking alone when she was attacked from behind and hit on the head, Tobias said. She was pulled into nearby bushes, but three bystanders heard the commotion and ran to her, causing her attacker to flee, he said.

Another attack happened around 3 a.m. September 5, said University of Florida Police Chief Linda Stump.

The 24-year-old victim described her attacker as white with scruffy facial hair. He was about 6-foot-2 and 240 pounds and wearing an orange button-down shirt and blue shorts, Stump said.

The attacker punched his victim in the face and then ran down the street, Stump said.

Then around 8:45 p.m. September 7, a 20-year-old woman was leaving a campus library and walking down a sidewalk when she was grabbed from behind, gripped by her hair and neck, Stump said. The woman fought her attacker, kicking him, and he ran away.

The university has doubled its effort to provide safety escorts for students through its SNAP program, and when resources cannot be provided to a student in ample time, "we'll pick them up in a police car if we have to," said Stump.

The campus police staff has been shifted to better cover night hours, she said, noting that the campus stretches over 2,000 acres.

"These situations are happening in seconds, and [the attacker] is fleeing," she said.

He may be ducking into a building and blending in. "In a heartbeat," Stump said, "he can be gone."

Asked whether she had a message for the attacker, the university police chief replied, "We're coming after you."