Wet concrete strikes, injures 4 workers in Calif.

By the Associated Press | August 31, 2011 | 2:55 PM EDT

SAN FRANCISCO (AP) — Four construction workers were injured Wednesday, three critically, after wet concrete fell on them as they worked on a multistory building, city authorities said.

Concrete being poured on the roof of the six-story building struck the workers around 8 a.m. Wednesday, covering them in sludge. Two of the workers fell about 30 feet after being hit, Fire Department spokeswoman Mindy Talmadge said.

All four were taken to San Francisco General Hospital, where three of them were listed in critical condition, Talmadge said. The fourth worker's injuries were not life-threatening.

The workers, whose names have not been released, were employed by Nibbi Brothers General Contractors of San Francisco. A message left for company officials was not immediately returned.

State workplace safety investigators and city building inspectors were on the scene in the city's Dogpatch neighborhood to investigate. Work resumed on the $40 million apartment complex later Wednesday morning.

State inspections of the job site in January and July found no safety violations, the San Francisco Chronicle reported.