Story highlights 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

Students at the University of Florida are being warned about a string of vicious assaults against women near and on the Gainesville campus, and multiple law enforcement agencies are asking for the public's help in finding the attacker.

There have been at least four attacks with 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.

The latest attacks have young women in the community on edge.

"My mom got me a stun gun as soon as I told her about it," student Amanda Clark told CNN. "I'm afraid to walk to my car. My friends and I are calling each other to find someone to walk with us, or sometimes the campus police program for an escort at night. It's scary."

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.

The circumstances of the various attacks are similar:

-- 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.

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.

"This is a pattern of repetitive behavior is getting to the point where we need to step up and we need to say we need your assistance. We need all your attention drawn to this. This is a pattern of repetitive behavior," Stump said in a news conference Monday.

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.

Four law enforcement agencies are working to solve the case. But police say the 2,000-acre campus and large student body population make it easy for someone to disappear.

"These incidents are happening very quickly on campus and in a heartbeat he can be gone, he can blend in. We need a break. We need eyes and ears," Stump said.

The campus police staff has been shifted to better cover night hours, she said.

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

The attempted sexual assaults are happening 24 years to the week when serial killer Danny Rolling stalked and killed five students -- mostly women -- who attended university in August 1990.

The attacks in that case ended in death and dismemberment.

Rolling confessed to the murders and eventually was executed in 2006. A memorial to the five students he killed remains on campus.

David Kratzer, vice president of student affairs, reflected Monday on those difficult days in 1990.

"This community came together, unified and I really think that the closeness that was forged during that terrible time really is what you are seeing today."