"We know the line where it was contacted was 40 inches below ground, so at this point the investigators are going to look at what led to the equipment coming in contact with the line that far underground," said PG&E spokesperson Denny Boyles.
Boyles says the amount of gas released is the equivalent of what 10,000 homes would use. A Fresno County Public Works employee was digging at the site, but PG&E crews say no call was made to notify them of the work being done. In California, contractors are required to tell PG&E crews if they're going to dig, or else they can face fines.
"What we're waiting for right now is the investigations to be complete, and then we can begin that work to do the repairs," said Boyles.
The explosion rocked nearby neighborhoods Friday afternoon, and some witnesses could see it from nearly 20 miles away.
"It went like above the trees, and it was really close," said witness Adrianna Vasquez.
A Fresno County work crew, investigators say, likely struck a large gas main with a backhoe, creating a fiery ball of smoke for hours.
"There is a large crater where the explosion occurred. The front loader is completely blackened and of course irreparable," said Fresno County Sheriff Margaret Mims.
The explosion happened at the peace officers firing range where inmates and deputies were working. On Saturday, seven out of the 11 people taken to nearby hospitals were still receiving treatment. Two of those remain in critical condition.