While being demolished, a three-story building partly collapsed onto a road near this city's East Third Ring Road on Friday.

The accident caused no injuries but damaged four vehicles that were passing by.

The building stands near the new China Central Television (CCTV) building in Beijing's Central Business District.

It collapsed onto Chaoyang Road at about 11:10 am, Wang Yu, a Chaoyang District police officer, said on Friday afternoon.

"We received a phone call saying a building had collapsed in the Chaoyang district," Wang said. "We immediately dispatched more than 20 policemen to keep order there."

The building was being demolished by a company named Hua'ao House Demolition Ltd, which could not be reached for comment by press time. The reason for the accident is still unknown.

Wang Yanlong, a 50-year-old newspaper seller who witnessed the accident, said four vehicles were damaged by the collapsing building - one seriously and the other three less so.

"I heard a loud noise at about 11:10 am," Wang said. "I rushed out of my stand and saw a collapsed building was blocking the main road."

Steel and iron bars from the building pierced the trunk of a passing car, destroying it. The driver, a middle-aged man, got out immediately, Wang said.

"The driver talked with me for a while afterward, and I could see that he was really frightened," Wang said. "The driver said he was trying to turn left when he saw the building was collapsing but couldn't keep his car from being hit."

Wang said the accident blocked the eastbound lanes of Chaoyang Road and brought traffic to a standstill for about half an hour.

Yao Yong, a musician who said the collapse had destroyed his vehicle, uploaded a photo of the accident site onto his Sina micro blog on Friday. The picture showed that the roof of his SUV had been pierced by a steel bar directly above its back seat.

"If I hadn't turned the steering wheel hard right after I saw that the wall was collapsing, the steel bar would have jabbed me in the head after it went through the SUV's roof," Yao said on his micro blog.

By about 6 pm on Friday, Chaoyang Road had been cleared and the flow of traffic had been partly restored. A side road, though, was still blocked by debris.