After a gasoline tanker truck overturned and caught fire, a section of freeway that funnels traffic off the San Francisco-Oakland Bay Bridge collapsed.
The heat was intense enough to melt part of the freeway and cause the collapse, but the truck's driver walked away from the scene with second-degree burns.
No other injuries were reported, which officials said was only possible because the accident happened so early on a Sunday morning. The truck driver took a taxi to a nearby hospital, Officer Trent Cross of the California Highway Patrol said.
Authorities said the damage could take months to repair, and that it would cause the worst disruption for Bay Area commuters since the 1989 Loma Prieta earthquake damaged a section of the Bay Bridge itself.
Transportation officials said they already had added trains to the Bay Area Rapid Transit light rail system that takes commuters across San Francisco Bay, and were urging people to telecommute if possible.
State officials said motorists who try to take alternate routes Monday instead of relying on public transportation would face nightmarish commutes.
The gasoline tanker ignited around 3:45 a.m. after crashing into a pylon on the interchange, which connects westbound lanes of Interstate 80 to southbound I-880, on the edge of downtown Oakland about half a mile from the Bay Bridge's toll plaza.
A preliminary investigation indicated he may have been speeding on the curving road, Cross said.
The fire melted a second interchange from eastbound I-80 to eastbound I-580 located above the first interchange, causing a 250-yard (228-meter) section of the roadway to collapse onto the roadway below, according to the highway patrol.
Witnesses reported flames from the blaze reached up to 200 feet (60 meters) high.
The Bay Bridge consists of two heavily traveled, double-decked bridges about two miles (3.2 kilometers) long straddling San Francisco Bay. State transportation officials said 280,000 commuters take the bridge into San Francisco each day.