A freak flash flood caused by heavy rainfall in Pittsburgh, killed at least four people.The body of the possible fourth victim has been found, authorities said on Saturday. The heavy deluge overwhelmed the city's sewer system during rush hour, submerging dozens of vehicles along a street near the Allegheny River.

Kimberly Griffith, 45, and her daughters Brenna, 12, and Mikaela, 8, drowned in their car on Friday and were pronounced dead at the scene around 6 p.m., a spokeswoman for the Allegheny County medical examiner's office said on Saturday.

The mother and her two daughters were trapped inside their vehicle when rushing waters pinned their car against a tree. They were unable to escape when water as deep as nine feet engulfed their vehicle on a low-lying section of the city's Washington Boulevard near the Allegheny River.

Rescue workers have also recovered the body of Mary Saflin, 72, of Oakmont, Pa., who was reported missing during the flood, Raymond DeMichiei, the city's deputy director of emergency management, said on Saturday.

The city experienced heavy storm and flooding shortly after 4 p.m. on Friday, said Michael Huss, Pittsburgh director of Public Safety. Dozens of vehicles were stranded along the road near Allegheny River. The area that got flooded has hills on either side, creating a valley through which the street runs. When rain falls, it rushes into the roadway, DeMichiei said.

Water was as deep as 9 to 10 feet along some stretches of the road. Commuters scrambled to the roof of their cars or held on to heavy items to keep from being swept away. Paramedics in boats went from car to car to rescue drivers and passengers. An earlier storm in the morning had also brought about an inch of water. The flood resulted in power outages in parts of the city late Friday afternoon.