(Adds details from news conference)
PITTSBURGH, Aug 19 (Reuters) - Flash flooding killed at least three people in Pittsburgh on Friday when heavy rains submerged cars in water that was 9 feet deep in places, authorities said.
The three victims, identified as a woman and two children, died after their vehicle was pinned against a tree and they were unable to escape, Michael Huss, the city's public safety director, said in a press conference broadcast in part on local KDKA-TV.
Huss said the water was more than 9 feet deep in some areas along the road, which is near the banks of the Allegheny River. An elderly woman remains unaccounted for, he said.
"We have crews that are continuing to search," he said.
Some 18 cars were stranded in the flooding and 11 people had to be rescued, according to local media reports.
Accuweather.com said rescue crews used inflatable rafts to reach stranded drivers. Electrical ower was out to 8,400 customers.
(Writing by Cynthia Johnston; Editing by Peter Bohan and Bill Trott)
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