The gunman remained at large early Sunday, authorities said.
Some 500 students, faculty and staff attended a Saturday evening prayer service at the school for Jessica Moore, 19. Moore's parents, grandparents and uncle were also on campus, mourning her death and praying for her.
After the service, Christian Powe, who said he and Moore were first classmates and then "real tight" after sharing an oral rhetoric class together, called her someone "you can really open up to."
She was nicknamed "Tennessee," he said, a nod to her roots there, and said she was a fan of the NBA's Los Angeles Lakers, texting him the scores of their games when he couldn't watch them on TV.
He had returned from a college retreat in Pennsylvania for the prayer service.
"She had a magnetic personality," he said.
Moore had been at the party early Saturday when a fight started after a man was kicked out because he didn't want to pay the cover charge, said a student who said she attended the party and had classes with Moore. The woman did not give her name, citing fears for her safety because the shooter was not in custody.
She said the man came back and began firing, sending screaming partygoers rushing out the door and climbing out windows.
The other four victims were hospitalized with non-life-threatening injuries, and one was released, said East Orange Police Sgt. Andrew Di Elmo.
The victims did not know the shooter, who fled from the apartment on foot, Di Elmo said. Police offered a $10,000 reward for information leading to the suspect's capture.
Police said that two of the wounded are both 19-year-old women who go to Seton Hall, and one is a 25-year-old man who attends the New Jersey Institute of Technology. The fifth victim is a 20-year-old man from New York City who is not a student.
Seton Hall, a private Catholic university in nearby South Orange, about 15 miles west of New York City, enrolls about 10,000 students.
Moore was a sophomore honors student from Disputanta, Va., majoring in psychology, said the university's interim president, Gabriel Esteban, who appeared to be on the verge of tears during a news conference on campus.
Police were not releasing the other victims' names because the shooter wasn't in custody, Di Elmo said.
Mary Williams, a 59-year-old retiree who lives next door, said she was in bed when she heard the gunshots, and she called 911.
"I seen people scattering, climbing out the window, trying to get out the front door, back windows, a lot of hollering and screaming," Williams said in a telephone interview.
A number of people who fled the house sought refuge at a White Castle restaurant down the street, said Vanie Estime, an employee there.
"I was doing the drive-in and I heard screaming through my headset," she said.
The apartment is less than a mile from the university. Well-kept row homes line the street, but a main cross street leads to a tougher part of town.
The school's Department of Public Safety urged students to "travel in groups when walking off campus."
Student Connor McCormick, of Colchester, Vt., said the school sends campuswide e-mails whenever a mugging occurs.
"We probably get one a week," said McCormick, 19, adding than when students go off campus, "You don't walk alone."
The suspect is described by Seton Hall Public Safety as an African-American, approximately 25 years old and 5-foot-8, with a full beard and wearing a white tank top. He was allegedly joined by a second African-American male on a bike with dreadlocks and wearing red shorts, according to the University paper, The Setonian.
A $10,000 reward is being offered by the sheriff's office for information leading to an arrest.