The National Transportation Safety Board's preliminary report there are no conclusions drawn on what caused the explosion, but it does lay out some disturbing facts that PG&E has yet to address.
The report says the explosion happened at about 6:11 p.m., but that PG&E did not dispatch a crew to close the nearest mainline valves until 6:45 p.m. -- 33 minutes later. It then took until 7:40 p.m. to shut off both valves, an hour and 29 minutes after the blast and fire that ultimately killed eight people and destroyed 37 homes.
"That's very upsetting, this was horrendous," says San Bruno resident Connie Buschman.
Buschman's home is just a few doors away from those leveled in the disaster.
"I wasn't even in the house and we're all having emotional things, so it's going to make it harder for us to forgive PG&E if that's the way it really happened," says Buschman.
Congresswoman Jackie Speier, D-San Mateo, says, "Yesterday PG&E informed us in a general sense that automatic shut-off valves would be installed. That's a step in the right direction, but it should not divert our attention from the human failure, the 33-minute delay it took for someone at PG&E to dispatch crews to turn off the valves."
The NTSB report also shows it took until 11:30 p.m. to shut off the individual gas lines to burning homes.
"In the time of a disaster like this or tragedy or earthquake, is it going to take five hours to get that response?" asks Assembly member Jerry Hill, D-San Mateo.
The report explains why investigators gave so much attention to a PG&E power site in Milpitas, 40 miles away from the disaster.
There was a malfunction there just before the blast. When the power dropped, the regulating valve for the gas line opened all the way. Pressure in the line increased up to 386 pounds per square inch. That could turn out to be a significant number because, while PG&E lists the maximum safe pressure for the pipe at 400 PSIs, the original manufacturer rated it safe only to 375 psi.
PG&E issued a statement saying the preliminary report is a critical first step. PG&E President Chris Johns says, "We welcome it, and appreciate the painstaking efforts of the NTSB experts to conduct a thorough and comprehensive investigation to determine the root cause of this terrible accident."
PG&E is not explaining the delay in dispatching a crew nor is PG&E taking any direct questions for reporters at this time.
The final NTSB report may be months away.