Partygoers stampeded to escape gunfire that killed one college student and wounded 11 people at an Ohio fraternity house, authorities said Monday as they searched for a motive in the weekend shooting.

Jamail E. Johnson, 25, a senior at Youngstown State University, was shot to death early Sunday as he tried to separate two groups at an Omega Psi Phi fraternity house party. Authorities say there had been a dispute, two men had left the house and then returned and sprayed bullets into the crowd. Among the injured was a critically wounded 17-year-old.

When the shots rang out, “it was practically a stampede atmosphere,” according to witness accounts, city prosecutor Jay Macejko said.

Investigators did not know what the initial argument was about and had yet to determine a motive for the shooting, Youngstown Police Chief Jimmy Hughes said Monday. The two suspects were neither students at the university nor members of the fraternity, police said.

The two men, Braylon L. Rogers, 19, and Columbus E. Jones Jr., 22, were charged with aggravated murder, shooting into a house and 11 counts of felonious assault, said Hughes. They were being held at the Mahoning County Jail, said jail officials, who did not know whether the men were represented by attorneys.

Court appearances for the suspects scheduled for Monday morning were postponed until Tuesday, and the charges against them could undergo “adjustment,” Hughes said.

Johnson and the others were shot off-campus at a two-story brick house in a neighborhood of once-elegant homes, many of which are now boarded up. The house party had been bustling with 50 or more people early Sunday, the police chief said.

Johnson apparently was trying to separate two groups when he was shot, Capt. Rod Foley said. He was shot once in the head and multiple times in his hips and legs, said Dr. Joseph Ohr, a forensic pathologist with the coroner’s office. An autopsy is planned Monday.

The wounded ranged in age from 17 to 31; six were students. About half were shot in the foot, police said. Two were hit in the abdomen. The 17-year-old was wounded near one ear.

By Sunday afternoon, eight had been treated at a nearby hospital and released, spokeswoman Tina Creighton said. She said she could not release the conditions of the remaining three.

University president Cynthia Anderson said police assured her there was no threat to the campus.

Members of the university-sanctioned fraternity lived at the house, though Cooper said the fraternity does not own it. He said that after the shooting, Johnson’s fraternity brothers were “very solemn, very alarmed, very hurt.”

Johnson had recently traveled to North Carolina for a fraternity program emphasizing manhood and scholarship, said Christopher Cooper, a legal officer for Omega Psi Phi fraternity.

Johnson “was just an excellent, excellent young man, and our loss runs deep,” Cooper said.

“This is one of those days that every university president across the country, as well as many other officials, always dread,” Anderson said.

Roughly 15,000 students attend the urban campus in northeast Ohio near the Pennsylvania state line. The university planned to hold a prayer service on campus at noon Monday.

A neighbor, Rodger Brown, 54, said the house and an adjacent home with Greek lettering, indicating a fraternity, often have parties on weekends but had caused no problems in the neighborhood.'

“It’s a nice, quiet neighborhood,” Brown said.

Gov. John Kasich said he was “shocked and saddened” by the shootings. He offered the school the use of “any and all state resources they might require.”

Kasich planned to meet Monday in Youngstown with Anderson and Mayor Jay Williams to discuss the shootings.

The university said counselors and clergy also would be available to students and others on campus.