University of Chicago officials have identified the first victim of Saturday’s deadly shooting rampage as Yiran Fan, a 30-year-old PhD student of financial economics.

According to police, Jason Nightengale, 32, shot and killed Fan while the student was sitting in his car in a parking garage in the Hyde Park neighborhood. That shooting was the start of a spree in which Nightengale killed three people and wounded four others over the span of roughly four hours. The spree ended when Nightengale was killed in a shootout with Evanston police, miles from where Fan was murdered.

Investigators are trying to determine a motive for the attacks.

In an email to school alumni, university President Robert Zimmer and Provost Ka Yee Lee said Fan had moved to the U.S. from China for school and was in the fourth year of his PhD studies, with an eye toward proposing his dissertation later in the year

“This sudden and senseless loss of life causes us indescribable sorrow. In the days ahead we will come together as a community to mourn, and to lift up fellow members of our community in this difficult and very sad time,” the leaders wrote in the email.

The school is planning to maintain an increased police presence around the area of the killing, even though there’s no indication of an “ongoing threat.”

Chicago Police Superintendent David Brown said after the fatal shooting in the parking structure, Nightengale “just randomly” walked into an apartment building a block away, where he shot a 46-year-old security guard who was sitting at the desk and a 77-year-old woman who was getting her mail.

The guard was pronounced dead at a hospital and the older woman, who was shot in the head, was hospitalized in critical condition, according to police.

About 45 minutes later Nightengale went to another nearby building and stole a car from a man he knew. He then went to a convenience store and fired shots, killing a 20-year-old man and wounding an 81-year-old woman in the head and neck, Brown said. The woman was also in critical condition.

After leaving the store, Nightengale shot a 15-year-old girl who was riding in a car with her mother, leaving the girl in critical condition, police said. He then went back to the convenience store and fired on officers who were investigating the earlier shooting. No police were injured, Brown said.

Nightengale then drove about 25 miles north to suburban Evanston, where police responded to a report of shots that had been fired inside a CVS. Nightengale had apparently walked into the pharmacy, announced that he was robbing it and fired off shots that didn’t hit anyone, authorities said.

He then went across the street to an IHOP restaurant, where he shot a woman in the neck. She was in critical condition, Evanston police Chief Demitrous Cook told reporters.

Nightengale left the restaurant and was confronted by officers in a parking lot, leading to a shootout in which he was shot and killed, Cook said.

“But for the brave conduct of Evanston police officers confronting this suspect, many more people would have been injured,” Brown said.

In a statement, Evanston Mayor Stephen Hagerty said the quick response of Evanston police “brought the bloodshed to an end in a busy commercial area before anyone else could be hurt or killed.”

“While we are still learning more about the offender, his motive, and the totality of yesterday’s tragic events, one thing is clear: If not for the brave actions of Evanston and Chicago police, many more innocent lives would have been lost,” Hagerty said.

Brown said investigators had very little information about Nightengale but plan to release more details as they get them.

And he defended police when asked at a news conference how it was possible for Nightengale to make it all the way from the South Side of Chicago to Evanston on a murderous rampage.

“When you hear this whole story, it seems that you have a crystal ball of what he’s doing next, and we all know we don’t have a crystal ball where he goes next nor do we have this on any of our POD cameras,” Brown said. “We are responding to the scene as these crimes are happening, getting information, and again, he’s going to the next while we are trying to keep up with what’s happened previously.”