Maryland ? A massive, aging water main ruptured Tuesday and sent a wave of water down a suburban Washington road, transforming the street into a raging river and trapping nine motorists who had to be rescued from the frigid deluge by emergency workers in helicopters and boats.

The water gushed down River Road in Bethesda and rocked cars. Two people in a minivan were plucked by helicopter out of the roaring rapids, water crashing and spraying 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. 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.