Read more about this story from CNN affiliate WTAE.
(CNN) -- A mother and two children drowned inside a car Friday after floodwater washed their vehicle away, a Pittsburgh city official said.
The city experienced a heavy storm and flooding shortly after 4 p.m. Friday, said Michael Huss, Pittsburgh director of Public Safety.
"The manhole covers began to lift from the rush of water, and the roadway flooded," Huss said.
CNN affiliate WTAE reported that the incident took place in the eastern Pittsburgh neighborhood of Highland Park in Pennsylvania.
Huss said the family's vehicle washed down the roadway and got stuck next to a tree.
"The three could not get out of the car before it was submerged," Huss said. "The water had a lot of force behind (it), and all three inside drowned."
In addition, Huss said, "We have one person whose car was located, but that person is still unaccounted for."
Dive units were searching late Friday night.