(CNN) -- The fourth and final suspect in the fatal shooting of two Arkansas university students turned himself in Monday, University of Central Arkansas police said.
The first suspect was apprehended while driving about three minutes after the Sunday night shooting. The others were detained later, said Lt. Preston Grumbles.
The suspects were identified as Kawin Brockton, 19; Kelsey Perry, 19; Mario Toney, 20 and Brandon Wade, 20.
Police released little details on the suspects other than the fact that they were not university students.
"It does not seem at this time that it was a random act," he said, but police are "unsure of the precise motive." He said there was "no indication" the shooting was gang-related.
University police released the names of the victims Monday. Ryan Henderson, 18, of Little Rock, Arkansas, and Chavares Block, 19, of Dermott, Arkansas, were killed. Block was a sophomore pre-engineering major. Henderson was a freshman who had not yet declared a major.
The university's student government will hold a candlelight vigil in memory of the students at 5 p.m. (6 p.m. ET) Monday. Religious organizations on campus will host a prayer vigil Tuesday.
A third victim, Martrevis Norman, was treated at a hospital and released. He is not a student at the university, said Lt. Rhonda Swindle of UCA campus police. A hospital representative earlier told CNN that the survivor was shot in the leg.
"This is something you pray never happens," interim university president Tom Courtway said, visibly upset. "But it happened."
The shots were fired near Arkansas Hall and the Snow Fine Arts Center at 9:22 p.m., Swindle said.
Freshman Sam Hausen, who was about 50 feet (15 meters) away from the shooters when the gunfire began, said, "I heard about five or 10 shots and, at first, I thought it was just firecrackers, because everybody always clowns around out there, but I just realized that it wasn't firecrackers."
As he began running away, he saw one of the wounded students hit the ground and another stumble into the dorm, he said.
"I saw a couple cars speed off," Hausen said. "I don't know if they were the shooters or not."
Student Lauren Knight, who was walking to the library when the shooting started, said students scurried for safety. When the campus lockdown was ordered, Knight was stuck with other students for several hours inside the library, she said.
The university serves about 12,500 full-time students in Conway.