Authorities say that the roof on a privately-owned prison in East Texas collapsed Saturday morning, resulting in the injuries of 20 inmates and trapping many more. The unit at the Diboll Correctional Center where the incident happened housed 84 inmates.

According to local television broadcaster ABC13, the collapse happened at 11:30 a.m. Saturday morning. The ceiling is reportedly made almost entirely of sheet rock.

Via ABC13:

All 19 were transported to a local hospital for evaluation. One was then flown to a hospital here in Houston. At this time, we don't know the condition of the patient who was airlifted. As for the others, we're told the injuries don't appear to be serious.

According to the Associated Press, a spokesperson for the prison could not confirm what caused the ceiling to collapse.

[Image via ABC13]