Alameda County Deputy Fire Chief Ryan Nishimoto said he did not know if those injured were workers or residents, but he said three people were immediately sent to a hospital due to their injuries and three others who were sent had more minor injuries.
Three structures on two separate lots were severely damaged, Nishimoto said. Some of the 75 firefighters who responded had to back off momentarily when they felt electric shocks from power lines that had fallen on the site.
The neighborhood of single-level homes with tidy small lawns and some businesses near two freeways had been undergoing construction work for wider sidewalks and bike lanes.
The explosion occurred in the unincorporated community of Ashland, near the city of Hayward.
The National Transportation Safety Board said Thursday it is sending a team to investigate.
Pacific Gas & Electric Co. was alerted around 7:35 a.m. that a construction crew — not with the utility — had damaged an underground gas line. Utility workers arrived to isolate the damaged line, but gas was leaking from various locations.
Workers stopped the flow of gas at 9:25 a.m., and the explosion followed shortly afterward.
Gas was flowing for two hours but the explosion happened 10 minutes after the line was shut off, PG&E spokesperson Tamar Sarkissian confirmed. She said it took time to isolate the line and stop the flow of gas.
The doorbell video showed a large excavator being used to dig in front of the home that exploded as a worker stood nearby.
Within moments, an explosion and flames blew out the walls and the roof of the home. People nearby appeared to be dazed for a few seconds, before running toward the home to search for any victims. Several workers lifted a large piece of debris from where it landed near the excavator.
Sirens could be heard in the distance as police arrived at the scene as flames began to spread at the site of the demolished building.
