Feds, State Investigating 3-Alarm Natural Gas Blast and Blaze in San Francisco

Updated Friday, Feb. 8, 4:30 p.m.:

In a press conference on Friday afternoon, an NTSB official told reporters that the investigative team will be working on the timeline of events surrounding the incident. Tomorrow the team plans to conduct more interviews and visit the pipeline control center.

With the help of the FBI, the NTSB is working to secure a 3-4 foot length of the pipeline that may be sent to Washington, D.C. for testing.

Original Post Feb. 7: State and federal officials have launched an investigation into a fire sparked by a ruptured high-pressure gas line in San Francisco's Inner Richmond neighborhood Wednesday afternoon — an incident that featured a two-hour struggle by PG&E crews to shut off the flow of highly flammable natural gas.

Despite the spectacular nature of the blast and fire, no injuries were reported.

An unknown number of people were displaced from up to seven residential units because of the fire. PG&E said about 300 gas customers and 2,500 electric customers lost service because of the blaze.

J.D. Guidi, a PG&E spokesman, said electricity was restored to all of the affected customers early Thursday morning. PG&E crews were working to remove water left over from the firefight in order to introduce gas back into the area's system.

Speaking to reporters as the fire roared nearby, San Francisco Fire Chief Joanne Hayes-White said a construction crew installing underground fiber-optic equipment touched off the fire by hitting the natural gas line.

The incident involved a worker using an excavator to dig a trench, according to Frank Polizzi, a spokesman for California's Division of Occupational Safety and Health.

A Verizon spokeswoman confirmed Thursday morning that one of its contractors was working in the area of the blast.

"Yesterday's fire in San Francisco's Inner Richmond District is tragic for the people impacted by the incident and resulting power outage," said Heidi Flato, a company representative, in a statement.

"MasTec, a vendor contracted by Verizon, was working at that location yesterday. We understand that MasTec is cooperating with investigators as they determine the root cause of the incident. The fiber installation has been halted pending the outcome of the investigation by local authorities," Flato said.

A top executive for MasTec, an infrastructure construction company based in Florida, expressed concern about the incident and said the company was conducting its own probe of the explosion.

"We want to express our deep concern for those affected by the gas line rupture," said John Higgins, president of MasTec's Utility Services Group, in a statement.

MasTec has been the subject of three previous Cal/OSHA inspections and two citations, according to Polizzi.

One of those infractions included a serious citation involving an incident in Concord in 2015. MasTec and other companies were working on a site to demolish high voltage overhead power lines when an employee of another firm "suffered an electric shock" as he cut into a riser that housed a live power line, Polizzi said in an email Thursday.

Polizzi said Cal/OSHA launched an investigation into the incident on Thursday. MasTec and two of its subcontractors, Advanced Fiber Works and Kilford Engineering, are the subject of that probe.

In Wednesday's incident contractors had called to determine where the gas lines where in the area, and PG&E marked where the lines were, according to PG&E spokeswoman Andrea Menniti. However, that does not indicate whether PG&E correctly marked the lines. Marking errors have caused serious problems in the past, including an explosion that destroyed a home in Carmel in 2014.

The California Public Utilities Commission is also investigating the incident, commission spokeswoman Terrie Prosper said in an email Thursday morning.

The National Transportation Safety Board plans to send a team to the area to investigate as well.

San Francisco Supervisor Catherine Stefani, who represents the district where the blaze occurred, said on Thursday that she plans to call for a hearing on the incident.

"I want to have [an] understanding of why this happened and how we can prevent it in the future," Stefani said.

"People want to understand. How could this happen? How could someone break into a line? ... Why did it take so long? [It took] two and a half hours ... people are very concerned about that. Those are two of the main things we’ll be looking at."

The San Francisco Fire Department said that it was alerted to the initial blast at 1:18 p.m. Wednesday. Flames continued to leap from the breached line for about two hours and 20 minutes until PG&E crews finally managed to stop the flow of gas fueling the blaze.

Firefighters then turned their attention to nearby buildings that had caught fire during the 140 minutes the flames roared from the rupture.

Crews from the utility used heavy equipment and hand tools in a frantic effort that involved digging into two locations in the street.

As crews excavated craters in the pavement nearby, PG&E spokesman Paul Doherty said the fire was caused "by third-party dig-in that had nothing to do" with the company.

Blair Jones, another PG&E spokesman, said it took time to shut off the gas because of "a complex array of utilities," including a 12-inch gas line, a 2-inch gas line, electrical lines and water mains, at the incident site.

Crews needed to proceed cautiously, Jones said, to avoid inadvertently disrupting gas and electric service over a wider area.

At least five buildings suffered damage in the blast and fire, Chief Hayes-White said, and firefighters continued to direct jets of water onto nearby buildings attempting to limit the spread of flames.

"Our job will become easier once PG&E does theirs," Hayes-White said before the gas stopped flowing, adding that it would be a complex task to shut down the gas line.

The main building involved in the blaze was Hong Kong Lounge II, a popular dim sum restaurant and night spot that appeared to have been gutted.

"This was an iconic restaurant, so many people have been very sad to see the damage done," said Supervisor Stefani of the lounge. "I let [the owners] know the city is here for them and we’re going to do whatever we can to help them."

Two other buildings are currently deemed uninhabitable, according to a statement from Stefani and San Francisco Mayor London Breed. And the city is working to help residents and businesses impacted by the blast.

"Thankfully no one was hurt as a result of this fire and our focus remains helping the people affected get back on their feet and connected with housing and services. I am working with our City departments to make sure that we provide every available resource at our disposal,” said Breed in the statement.

Residents could be eligible for assistance through the San Francisco Human Services Agency.

“We are here for the people who have been displaced and facing hardship because of this fire,” stated Trent Rhorer, Executive Director, San Francisco Human Services Agency. “People who have been affected by the fire are encouraged to take advantage of our City assistance programs, such as those that help renters find replacement housing while their homes are being repaired. Our hearts go out to these families.”

Impacted businesses may also tap into a Small Business Disaster Relief Fund through the Office of Economic and Workforce Development.

This post includes reporting from KQED's Raquel Maria Dillon and Kate Wolffe.