New video shows a New York State prison bus up in flames.

It happened on Route 9D, just north of I-84

Police say about 20 inmates made it out of the bus, leading to altercations among themselves, then with the officers.

One inmate suffered injuries, not considered to be serious, during the incident.

Witnesses say they saw the smoke from the highway.

"Me and my wife were driving, we saw a lot of smoke, we pulled over. And I noticed it was a state bus with inmates, so I recognized them. And the bus was on fire. People yelling, 'There's a fire!' on the bus in the back. We pulled over and I heard a guy screaming, and I saw that they were trying to get out. And we saw one or two of them fell down to the ground," said a witness.

State troopers on scene say a mechanical issue led to the bus fire.