Rain, traffic, land contribute to deadly Pa. flood

Workers clear vehicles from the scene of flash flood, caused by heavy rains, along Washington Blvd. where three people died while trapped in their car Friday, Aug. 19, 2011 in Pittsburgh. (AP Photo/Don Wright)

August 20, 2011 5:26:36 PM PDT
The flash flooding that killed four people and forced others to swim to safety or climb onto car roofs was a freak accident caused by heavy rainfall that overwhelmed the sewer system just as rush-hour traffic clogged low-lying city streets, officials said Saturday.