A brick facade that collapsed on a busy sidewalk, killing three people and injuring eight, apparently was improperly anchored and was pulled down by signs and iron shutters attached to it, officials say.

Don Kligerman, commissioner of the Department of Licenses and Inspections, said the accident Tuesday could lead to criminal charges.The two-story facade of two storefronts gave way shortly before 2:30 p.m. between Ninth and 10th streets on Market Street, one of the city's main arteries.

Among the 11 passers-by caught in the collapse were four police officers walking a beat. Two of the injured were seriously hurt.

"It happened so fast you couldn't see anything," said Alom Kadosh, manager of a stereo store. "But as soon as it happened people went outside and everybody pitched in to help pull off the bricks and the metal that covered the people that had been trapped underneath."

Neil Daniel was trying to fix his car when he heard a rumble and screams.

"I looked up and saw a wall of bricks coming at me and all I could do was close my eyes," he said.

The cause of the accident was under investigation, but authorities said they believed the wall was not properly anchored to the 19th-century building.

"It appears the weight of signs and security gates may have caused the collapse, but it will have to be checked by engineers," said Fire Commissioner Roger Ulshafer.

Kligerman said the owners of the building were cited in June for putting up the sign over a check-cashing agency without obtaining a zoning permit. He said the sign apparently extended too far over the sidewalk. The case has not reached court.

"The cumulative effect of that sign, the iron shutters and the wall that was just free standing - it was really just a matter of time until it fell over," Kligerman said.