An Oahu Community Correctional Center inmate died and his cellmate was arrested on suspicion of first-degree murder Saturday afternoon after a fight broke out between the two men, police said.

Joseph Tui Jr., 32, allegedly assaulted another inmate, 76, while they were in a holding unit cell at about 2 p.m. Saturday.

Tui was in OCCC for third-degree assault, but has convictions dating to 2000, including theft, burglary, escape, misdemeanor sex assault and harassment.

Ted Sakai, director of public safety, said at a news conference Sunday the fight happened during a 2 p.m. shift change while corrections officers were confirming a head count of inmates.

The officers heard "some loud noises of disturbance on the second floor of the holding unit," he said, and found the older man badly injured on the floor of the cell.

The cause of the fight is still being investigated. A killing committed by an imprisoned person qualifies as first-degree murder under Hawaii law.

Police said the older inmate suffered extensive head injuries and was taken to a hospital at about 3 p.m. after being tended to by OCCC medical and Emergency Medical Services personnel.

He died at 4:12 p.m., police said.

Officials have not released his name pending positive identification and notification of family members, but said he was awaiting trial on a charge of second-degree robbery.

Department of Public Safety spokeswoman Toni Schwartz said Tui was also taken to the hospital with injuries to his right wrist and left knee.

The inmates were in the holding unit for misconduct, Schwartz said. Tui was placed there on Thursday for threatening staff members, and the older inmate went in a few days earlier for cigarette possession.

Sakai said the inmates were sharing a cell because of overcrowding at the Kalihi facility.

"We have 36 cells in the holding unit," he said. "Two of them are out of commission because it’s a very old unit, and yesterday we had 49 inmates who needed to be separated (from the general population), so a number of cells had to be doubled up. Ideally, there would be one per cell, but we simply do not have enough cell space at this facility for that."

Sakai said staffing was not a problem in the unit, with a sergeant and three corrections officers present. He said a preliminary report by the department’s Internal Affairs Office found that officers followed procedures correctly.

Sakai acknowledged that officers cannot see all cells at any given time due to the design of the facility, and said building a new unit would help prevent another incident.

"The first thing is, we could use a new building, we could use a new unit, that’s the first thing," he said. "It’s a very old unit. It was designed and built in the 1930s. It’s the oldest building at this facility. The rest of the facility came up starting in the late 1970s, so it’s a holdover from another time."

Tui was in police custody Sunday and had not been charged pending further investigation.