A gas line at the Fresno County Sheriff’s gun range exploded Friday afternoon, injuring at least 11 people and bringing traffic on the nearby Highway 99 to a halt, the Associated Press reports.

According to the AP, the sheriff’s department said the explosion happened as a dirt berm was being built to confine gunfire to the range. A county public works employee was operating a front-loader as a group of county jail inmates did cleanup work nearby.

Fresno Fire Department spokesman Pete Martinez told the Los Angeles Times that the man operating the front-loader struck a gas line, which caused the explosion.

Ten of those injured in the blast were inmates, as well as the person operating the front-loader, the Fresno Bee reports. According to the Bee, as many as 13 people were injured, four critically.

“They can’t believe there weren’t any fatalities. If you saw the scene, it’s amazing people lived,” Fresno County Supervisor Henry R. Perea told the Bee. “There’s a crater out there.”

Image via LA Times. Contact the author of this post: brendan.oconnor@gawker.com.