"It's like an inferno, it was burning... really, really serious" said Justin Tin, a witness. "When he started soldering it and the sparks just exploded."
The four-alarm fire moved quickly across two buildings on San Bruno Avenue. It happened after a construction worker, hired to renovate one of the buildings, tried to hook up a gas line. The worker was critically injured and has life-threatening injuries. A firefighter was also transported to the hospital to be treated for heat exhaustion.
Once PG&E crews arrived, it took more than two hours to shut off the gas line -- something many residents find troubling.
"Our lives are in hand for this. What happens if they don't shut it off? I mean, the whole entire block could go up right? I mean, I'm a lot concerned," said Sherman Lee, a resident. "They're PG&E. They should know where to dig, right?"
San Francisco Fire Chief Joanne Hayes-White is also concerned. She said, "It will be an issue we'll address with PG&E. It did take longer than I would have anticipated."
When asked if two hours was too long, PG&E spokeswoman Brittany Chord said, "Every situation is different."
PG&E insists everyone followed protocol and the reason the shut off wasn't immediate is because the fire was right on top of the main gas cut off point, so a secondary shut off was used.
"As soon as we got the call, we sent out PG&E crews who assessed the situation and determined the safest way to shut off gas was to dig down into the street and squeeze it off there," said Chord.
A lot of people at the scene Tuesday compared this to the San Bruno explosion of 2010, but in that situation the gas line was a lot larger. The line at this fire was a one-inch line. Both PG&E and the San Francisco Fire Department are investigating.
Drivers on Highway 101 at the Interstate 280 split reported seeing smoke on the roadway.