Authorities are investigating after a photo shows a prison van driving down Interstate 270 with the back doors wide open.

The Montgomery County, Maryland, prisoners were secured and were not hurt, the county's sheriff's office told News4.

Capt. Maxwell Wee said the van was headed from the Montgomery County Correctional Facility near Clarksburg to a courthouse in Rockville about 7 a.m. when the doors flew open.

Wee said the doors were open for about 10 minutes before the problem was discovered. He said at least one person made a call to 911.

"They were restrained. I'm not going to get into all of the specifics, but there are restraints that we utilize to keep them immobile and also to safeguard during the transport," Wee said.

He said the van, a newer model, has been taken out of service and the doors were thoroughly examined.

"There are multiple doors on that vehicle and they should have been secured. It appears they were not secured. We are still looking into all the facts and circumstances ... but that's what it appears at this time," Wee said.