The explosion at the Fresno County Sherrif 's gun range happened on a Pacific Gas & Electric Co pipe carrying natural gas . An equipment operator and a group of jail inmates were expanding a road alongside Highway 99 , which was closed after explosion for two hours . Ten inmates and the operator were hospitalized , two of whom were in critical condition . Three inmates were evaluated and sent back to jail and three deputies were being evaluated for ringing ears and exposure to the hot blast . California Public Utilities Commission said it is investigating the explosion .
The explosion at the Fresno County Sherrif 's gun range happened on a Pacific Gas & Electric Co pipe carrying natural gas . An equipment operator and a group of jail inmates were expanding a road alongside Highway 99 , which was closed after explosion for three hours . Ten inmates and the operator were hospitalized , three of whom were in critical condition . Three inmates were evaluated and sent back to jail and two deputies were being evaluated for ringing ears and exposure to the hot blast . California Public Utilities Commission said it is investigating the explosion .