NTSB releases preliminary report on Hayward house explosion; gas detected after initial leak reported capped
By Carlos E. Castañeda
Federal investigators released an initial report on the explosion and fire that destroyed a home in an unincorporated area of Hayward last month, but they are still analyzing the handling of the response to a gas leak before the explosion.
The explosion in the community of Ashland on December 11, 2025, seriously injured three residents, along with three Pacific Gas and Electric workers. On Thursday, the National Transportation Safety Board released its preliminary report on the incident and events leading up to the explosion, indicating that PG&E detected gas near the home after an initial leak was reported to have been capped.
Investigators said a roadwork crew from Mayo Asphalt Milling damaged a 0.75-inch natural gas service line to a home at 868 E. Lewelling Boulevard, across the street from the home that ultimately blew up, shortly after 7:25 a.m., prompting PG&E to respond. Crews confirmed an active gas leak and initially told Alameda County firefighters that assistance was not needed, according to the preliminary report.
PG&E workers squeezed off the damaged service line about 8:18 a.m. and later detected gas near the home across the street at 867 E. Lewelling, the report said. Crews reported knocking on the doors of 867 E. Lewelling and two neighboring homes on both sides of it to warn residents, but said that no one answered.
At about 8:40 a.m., the PG&E crew began digging and squeezed off a 2-inch gas main at 9:29 a.m., stopping the flow in the gas main and service lines in front of 867 E. Lewelling, eight minutes before the home exploded, the report said.
The NTSB said the gas distribution system, which included steel pipelines installed in 1942, was operating within allowable pressure limits at the time. Damage estimates were still being determined.
The preliminary report said the investigation was still ongoing and will focus on physical evidence, safe excavation practices, and PG&E’s leak response and investigation procedures. The NTSB added that federal and state pipeline regulators, utility safety agencies, local fire officials, and PG&E are participating in the probe.
CBS News Bay Area has reached out to Mayo Asphalt Milling for a response, but the company – which public business listings indicate is based in Fremont – has not yet responded.
In a response to questions about its gas leak response, PG&E told CBS News Bay Area in a statement Friday that NTSB rules restrict communications about the investigation while it is pending
“The safety of the public, our customers and our coworkers is our highest responsibility. Our thoughts are with the residents and our PG&E coworkers who were injured during this incident,” a PG&E spokesperson said. “We want to thank the first responders from the Alameda County Fire Department who worked to make the area safe and minimize damage to property. We remain committed to working together with the CPUC, NTSB and other state and federal entities on the safe and reliable delivery of energy to our customers we are privileged to serve.”
