GRANITE, Okla. - More than a dozen inmates attacked each other with makeshift weapons at the Oklahoma State Reformatory yesterday, leaving two dead and 13 others injured in the melee, officials said.

Fights broke out about 12:30 p.m. in recreation yards of two of the medium-security prison's six housing units, said Jerry Massie, a spokesman for the Department of Corrections.

Most of the injured suffered cuts and stab wounds, and the entire incident was over in about five minutes, he said.

Three inmates taken to Jackson County Memorial Hospital were in critical condition, a hospital spokeswoman said.

Another inmate was reported in stable condition in Mangum City Hospital. Others were apparently brought to Elkview General Hospital in Hobart, but that hospital did not release any information.

"One fight started on one housing unit," Massie said. "They could be seen by the inmates on the other rec yard, and that triggered a second round of assaults."

No guards or prison staff were injured.

Prison officers on the yard ordered the inmates to stop fighting, and the inmates complied, Massie said. Guards did not fire any shots or release any tear gas, Massie said.

The prison remained locked down yesterday, with inmates confined to their cells.

Massie said officials believe home-made knives were used in the attack. The cause of the violence remains under investigation. *