It happened at the TDCJ Ferguson Unit. According to the Madison County Sheriff's Office, at around 1:15pm, three Navidad Oil employees were working on an oil battery on prison property when it exploded and caught fire.
All three employees were burned over 30 percent of their bodies. One of them jumped from the 25-foot structure and suffered a broken leg.
No prisoners or prison employees were hurt. The prison was put on lockdown shortly after the explosion.
At this point, the cause of the explosion is not known.