Bricks, rocks and debris crashed down onto a tour bus in Harlem last week when scaffolding at a demolition site collapsed. The work site accident injured as many as 18 people, according to authorities. Construction site accidents can often place workers in danger, but as the accident in Harlem illustrates passersby to a construction or demolition site can be exposed to personal injuries from an accident.

Among the 18 people injured in the scaffolding accident were bus passengers, building workers and two police officers, according to the Fire Department New York. NBC New York reports a pregnant woman suffered injuries as people around her scrambled for safety from the falling debris.

One witness says bricks and metal came raining down in the scaffolding accident. "People were walking underneath the scaffold when it collapsed," the witness tells NBC New York. Another man tells the news outlet that the structure "collapsed on the bus, on the street, on the sidewalk."

Prior to last week's accident, people previously reported falling debris at the work site. The Buildings Department fielded a complaint on Sept. 7 regarding falling bricks at the demolition site as workers used sledge hammers on the project. An inspection that same day revealed no violations.

One witness says he saw falling debris two weeks ago at the location. He says that as he walked down the sidewalk, "all of a sudden it started raining bricks."

The scaffolding accident occurred on Sept. 20 at 125th Street and Frederick Douglass Boulevard at the location of the demolition project. The FDNY reports that none of the 18 people injured suffered life-threatening injuries in the scaffolding accident.

Source: NBC New York, "Building Facade and Scaffolding Collapse onto Bus in Harlem: FDNY," Jonathan Vigliotti, DeMarco Morgan and Roseanne Colletti, Sept. 20, 2011