"Anybody with Farmers Insurance? Want to open up a claim?" shouted Doug Wong, a general adjustor with the agency.
The explosion Thursday evoked memories for many in the area of a deadly November 2004 pipeline explosion in Walnut Creek, which is across San Francisco Bay from San Bruno.
In that incident, a 60-foot pillar of fire erupted from a punctured Kinder-Morgan petroleum pipeline beside Las Lomas High School when a backhoe apparently clipped the high-pressure fuel line. Contractors were working to install a massive water pipe for the East Bay Municipal Utility District just a few feet from the fuel line's path. A clear account of casualties Thursday was not immediately available, but hospital officials reported caring for badly burned patients.
A man and a woman in serious condition were being treated at San Francisco General Hospital, a spokeswoman said.
The two, spokeswoman Rachale Kagan said, "were in critical condition due to the burns."
At least three other badly burned patients were taken to St. Francis Hospital in San Francisco, a spokeswoman said.
At Peninsula Medical Center in Millbrae, medical personnel were treating 10 patients with minor burns. The facility had declared a trauma alert, calling in extra personnel to deal with the emergency.
As flames continued to rage out of control in San Bruno, fire crews from outlying cities and agencies poured in to help.
Four air tankers, two smaller attack planes and 25 fire engines from the California Department of Forestry and Fire Protection were headed to the blaze, the agency said.
Off-duty firefighters, some of them without their protective gear, were battling the blaze alongside overwhelmed crews from the small San Bruno Fire Department, according to news reports.
The Blood Center of the Pacific issued an emergency alert and asked for people to donate blood Friday.
At San Francis Hospital, a major burn center, medical crews were gearing up to treat more patients.
"We do expect more victims," said spokeswoman Theresa Edison.
Times staff writers Megan Garvey, Maura Dolan, Lee Romney and Rong-Gong Lin II contributed to this report.