A cyclist rides past a memorial of flowers Monday where Karim Abou Najm, a graduating senior at UC Davis, was fatally stabbed Saturday in Sycamore Park in Davis, California.
CNN  — 

Three brutal stabbings near the University of California at Davis in the span of five days have left two people dead and some students rattled and fearful as authorities dig for clues on who is responsible and whether the attacks were connected.

The latest attack happened Monday night near campus and left a woman in critical condition. Just days before, stabbings at two parks near campus claimed the lives of UC Davis senior Karim Abou Najm on Saturday and David Breaux on Thursday.

The violence has put the college community on edge and prompted officials to ramp up security measures and urge students to be ultra-vigilant.

“Nobody should go into class knowing they have a risk of getting murdered. It’s just not worth it,” UC-Davis sophomore Henry Li told CNN. He added that he’s considering leaving town for the summer or even transferring to another school.

Davis Police have stopped short of issuing a curfew, saying it’s an extraordinary move at this time. It remains unclear whether the attacks were linked, though police have noted some similarities surrounding how they were carried out.

Elaine Lu, a recent graduate of UC Davis, was visiting campus and said the town had always felt safe – until now. She and her friends decided to stay inside at night following the attacks, she said.

“This kind of thing never happened before. After this murder, everyone is going to be so intimidated about it. I hope the school can improve their safety,” Lu told CNN.

On Tuesday, Chancellor Gary S. May announced all classes ending after 6 p.m. would be taught virtually instead of in classrooms. That change, which Li said made him feel safer, began Tuesday, and will remain in place indefinitely.

“We are aware of how troubling this is to the community. It’s making people fearful and anxious, and we encourage the community to take advantage of whatever resources are available,” May said during a news briefing Tuesday.

Police patrols on campus and around the city have been increased, with help from hired security and police from the UC San Francisco and UC Berkeley, according to UC Davis Police Chief Joseph A. Farrow.

The university is encouraging campus evening events to either go virtual or be rescheduled, the school posted Wednesday. It also expanded its Safe Rides program, which provides students with transportation to other campus locations or within the city from 8 p.m. – two hours earlier than its previous starting time – until 3 a.m.

Investigators hoping DNA could link crimes

As officials try to ensure the community’s safety, they are combing through details to find connections between the stabbings.

“We are looking for DNA that will help us find the offender. Unlike on TV, it can often take much longer to actually analyze that evidence and do comparisons,” Davis Police Chief Darren Pytel said during a news conference on Tuesday.

The investigation so far has shown some similarities between the attacks.

The two homicides happened in city parks, while the third attack against a woman on Monday occurred in an area police have called a “known transient camp.”

Additionally, the assailant or assailants in the second homicide on Saturday and Monday night’s attack both interacted with witnesses. That suggests bold behavior that causes police “significant concern,” Pytel said.

Also, the descriptions of the suspects in Saturday’s killing and Monday’s attack are “remarkably similar,” Pytel said.

The suspect in Saturday’s fatal stabbing is believed to be a “light-skinned male, possibly Hispanic,” between 19 and 23 years old and between 5 feet-7 and -8 inches tall with long curly hair, Davis Police said. The attacker on Monday was described as a man with curly hair, a thin build and a light complexion between 5-feet-6 and -9 inches tall, city officials said.

“At this stage we can’t definitively link them yet,” Deputy Chief Todd Henry told John Berman on “CNN News Central” on Tuesday. “It is very difficult to determine whether it was the same knife used in all three incidents, but the pattern of the attack and the severity of the attacks with a knife is very similar.”

Physical evidence has been submitted to crime labs to determine whether there’s a common thread. Three crime labs including FBI, state and one in Sacramento County are conducting the analysis.

Investigators work at a crime scene in Davis, California, on May 2.

Community mourns the victims

While investigators work to apprehend the attacker or attackers, the victims’ loved ones are in mourning.

Abou Najm, 20, was killed Saturday evening when he was on his way home from an undergraduate award ceremony, his family told KCRA.

“I want this to be his memory: a bundle of energy, a bundle of positivity,” Majdi Abou Najm said of his son. “Someone who was full of ambition, proud of his roots, who just wanted to make this world a better place.”

Karim Abou Najm was stabbed to death Saturday evening at a local park, according to UC Davis officials.

Abou Najm, who studied computer science, was on a path to a bright future and was extremely kind to people, his classmate Brayden Chipman told KCRA.

“Someone got robbed of their future,” Chipman told KCRA. “It’s just heartless, people doing things like that. Seeing someone that I know, it’s just felt a little deeply. It’s really sad.”

Breaux, 50, was a fixture in the community known as “Compassion Guy,” according to a statement from the mayor and City Council that said he regularly asked passersby about their views on compassion.

“The death of David Breaux is utterly and completely devastating,” Davis Mayor Will Arnold said. “Many of us knew David. We talked with him. We shared in his vision for a kinder world.”

David Breaux was fatally stabbed in Davis, California, on April 27.

Breaux’s sister said he was on a lifelong journey to develop a collective definition of “compassion” and had recently chosen to live outside in an area of Davis he felt safe in.

He had told his sister he could be vulnerable to threats and once urged her to forgive anyone who may harm him.

In a Facebook message Maria Breaux received from her brother in 2016, he wrote, “If I’m ever harmed, unable to speak for myself, forgive the perpetrator and help others forgive that person.”

CNN’s Natasha Chen, Jeffrey Kopp, Cheri Mossburg, Tina Burnside, Taylor Romine, Mitchell McCluskey and Dakin Andone contributed to this report.