Ventura Blvd. Blocked by Fallen Tree : Traffic: Lanes are closed when a pine topples onto a passing car during rush hour. Injured driver is taken to hospital.

A pine tree mysteriously toppled across Ventura Boulevard during rush hour Monday, slamming down on a passing car--apparently without seriously injuring the driver--and blocking the boulevard for hours.

The evergreen gridlock continued Monday night as city street maintenance workers tried to clear the tree from the San Fernando Valley’s busy main street. One of the westbound lanes of the boulevard remained closed late into the night, although the eastbound lanes and one westbound lane were opened to traffic several hours after the tree fell.

Authorities said they were unsure what caused the tree to fall about 6:40 p.m. from the place where it grew next to the sidewalk in front of an empty office building just east of Zelzah Avenue.

“We just heard something like a crack, and then a boom! It was very loud,” said Armando Castro, a service manager at a nearby Unocal station.

Motorists were routed to side streets as maintenance workers tried to chop up the massive trunk and cart it from the boulevard. One section was removed to reopen the sidewalk.

“It is a very big tree,” Castro reported.

Randy Perras, an assistant manager at the Ralphs supermarket across the street, said a woman rushed into the store asking for ice for the injured driver whose car was struck.

“I’m sure every attorney in Encino is out there with their business card,” Perras said.

The driver was taken to Tarzana Medical Center with injuries that were not life-threatening, police Sgt. Bill Maarschalk said.

Despite the closure of the boulevard, and a traffic jam that extended for blocks in either direction, Perras reported brisk sales at Ralphs.

“Business is very strong tonight,” he said. “I guess because everybody is driving through the parking lot to get around.”