A seven-alarm fire erupted early Wednesday when a gasoline tanker truck overturned, setting off 100-foot-high walls of flame and burning "a country block" of homes and apartments.

Flames licked up from opened manhole covers in cul-de-sacs in the Sacramento suburb as burning gasoline spilled into storm drains."We were asleep in our apartment and heard stuff blowing up outside. We looked out and it was cars exploding in the parking lot," said Michelle Sumrall, who fled in her bathrobe and boarded an evacuation bus at dawn.

"It looked like the Fourth of July," she said.

More than 100 firefighters evacuated an area of two square miles, including a convalescent hospital. Two houses were destroyed and two were damaged, Sacramento Fire Protection District officials said.

A firefighter, the tanker truck driver and one resident suffered minor injuries, said Battalion Chief Dennis Plessas of the American River Fire Protection District.

The fire started at 3:05 a.m. when the tanker loaded with 8,400 gallons of gasoline turned over about half a mile from the American River and about 10 miles from where the American and Sacramento rivers meet, fire officials said.

It quickly reached seven alarms and threatened houses along a "country block," a fire dispatcher said.

Plessas said more than 300 people were evacuated.

Firefighters from around Sacramento County fought dozens of spot fires until the fire was brought under control by 6 a.m. They used sand and tanker vacuum pumps in an effort to stop the gasoline before it spread to the American River.

The cause of the tanker accident could not be immediately determined. But it appeared to be a single-vehicle accident, officials said.