Cars try to make their way through water from a break in a nearly 5 1/2-foot water main Tuesday in Bethesda, Md.
The water gushed down River Road and rocked cars. Two people in a minivan were plucked by helicopter out of the rapids, water crashing around them as they were lifted to safety in a basket. Other motorists escaped 4-feet deep water by boat.
Montgomery County fire officials said five people were checked for hypothermia; temperatures outside were in the 20s.
"The water tumbled over the car like a wave," said Silvia Saldana, of Springfield, Va., who was traveling to work when she became trapped. "I started to pray."
It was not immediately clear what caused the pipe to burst. Temperature, age and other factors can contribute to water main breaks.
Fire spokesman Pete Piringer said crews had trouble getting to people because of the swift-moving water. Officials said 150,000 gallons of water per minute were rushing out at one point, spilling rocks, dirt and other debris onto the road.
Trees fell onto a power line and knocked down a utility pole. Schools in the county closed early because of widespread water outages. A hospital where three people rescued were treated and released diverted ambulances and closed its trauma division because of lost water pressure.
Hebert De Rienzo tried to turn his hatchback around as water began rising in and around his car.
"We couldn't open the windows because the water would come through," he said. "We were scared."
A man who lives about 50 feet from the street described the unexpected flood after the pipe, about 5 1/2 feet in diameter, ruptured.
"I thought it might be a minor leak, then suddenly I stepped outside and, 'My God!"' said Raj Bhansaly. "It looked literally like the Potomac River."
Firefighter Anthony Bell was on a fire truck when he saw brown water on the road and realized something wasn't right.
"We were wondering if we could make the rescue," he said. Bell and other firefighters raced through the water and pulled four people from cars.
"I've been here 20 years," he said, "and I've never seen anything like this."
John White, a Washington Suburban Sanitary Commission spokesman, said it was not yet clear what caused the break.
Because of the water's intensity, fire officials didn't allow utility workers to immediately shut down valves where the break occurred, White said. But crews were able to shut down valves farther down the pipeline, stopping the flow. Authorities said the water went into a nearby creek.
Water pressure was being restored late Tuesday to hundreds of customers, including the National Institutes of Health and the Food and Drug Administration, which are located in the area.
There have been several major water main breaks this year in the wealthy suburb of Montgomery County. In June, a rupture closed more than 800 restaurants and left tens of thousands of people scrambling for clean drinking water.
The sanitation commission has warned its system is aging, overtaxed and underfunded. It serves 1.8 million suburban Maryland customers and has had an increasing number of water main breaks, including 1,357 between January and November this year. Last year, it had a record 2,129 breaks or leaks.
White said the pipe that broke Tuesday was installed in 1964.
The American Water Works Association, a Denver-based not-for-profit that works to improve water quality, said billions of dollars are needed to replace aging pipes nationwide.
Spokesman Greg Kail said old pipes continue to be a major factor in water main breaks. Some pipes are 50 to 100 years old, he said.
"We are seeing a higher rate of breaks nationwide," he said. "We expect that rate to increase in the next 10 to 20 years."
Associated Press writers Brian Westley and Nafeesa Syeed in Washington and AP photographer Jacquelyn Martin in Bethesda contributed to this story.