UPDATE: One Shot, Several Stabbed During Riot At New Folsom Prison

REPRESA (CBS13) - One prisoner was shot by a guard and several more suffered stab wounds during a large-scale riot at New Folsom Prison on Wednesday.

The fight broke out at 11:17 a.m. in one of the maximum-security population yards at California State Prison, Sacramento, according to prison spokeswoman Terry Thornton.

"To our knowledge there has been no tension on the yard," state corrections Lt. Tony Quinn said.

But Wednesday there was as more than a dozen ambulances moved in and out of the New Folsom Prison after an explosive riot.

"We think this was spontaneous," Quinn said.

The inmates were socializing in the exercise yard when a major fight broke out.

Startled by what was taking place, correctional officers scrambled to get the maximum-security prison locked down all the while keeping officers safe.

"So this is something that caught everybody, including our staff, off guard," Quinn said.

One officer fired off a warning shot, forcing inmates to the ground, but within seconds they were up again.

Some apparently stabbed others with homemade knives, better known as shanks. Thornton said 10 prisoners suffered stab wounds.

"Just based on the injuries, we know that they were stabbing-type devices, ice-pick style weapons," Quinn said.

Some inmates were also severely beaten by other inmates. In all, 13 inmates were hospitalized and the riot 60-70 prisoners. No officers were injured.

Quinn said an officer was then forced to fire a second round, striking one inmate in the thigh. That's when the fighting stopped.

Quinn was asked if gang retaliation triggered the riot.

"It takes a couple of days to figure this out," he said. "We'll go over the surveillance video. Sometimes in these riots guys are just trying to get out of the way. They're not really involved, so it takes a day or two to try and figure out who was actually involved and who was just a victim of wrong place, wrong time."