GRANITE, Okla. (AP) — More than a dozen inmates attacked each other with makeshift weapons at the Oklahoma State Reformatory Monday, 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 transported to Jackson County Memorial Hospital were in critical condition, a hospital spokeswoman said.

No guards or prison staff were injured.