David Polikoff, a Montgomery County firefighter, had never seen floodwaters moving so fast as he jumped off his truck late Tuesday evening. Massachusetts Avenue looked like the rapids he had watched kayakers hurl through on television.

Three cars with four people in them were stranded near the intersection of Massachusetts and Little Falls Parkway, and the water was rising.

Polikoff had watched others perform rescues in fast-moving water, but he had never done it himself. He knew that the swift-water rescue experts were on their way.

"But we couldn't wait," he said.

He and his partners, Peter Mayo and Dave Horwatt, donned life jackets and waded into the waist-high flash flood -- one of many unleashed by more than four inches of rain that drenched some parts of the Washington region Tuesday evening, falling in some places in less than two hours.

With so much rain falling so fast, low-lying roads, underpasses, creeks and canals burst to overflowing. Most of the floodwater had receded by yesterday morning. Crews worked to clear debris and tree limbs from roadways and to restore power to downed traffic lights in time for the afternoon rush hour.

One of the worst backups was on westbound Interstate 66 in Virginia, where debris blocking a storm-water drain near the Route 7 interchange created pools of water as much as six feet deep and caused traffic to back up for miles from 10 p.m. Tuesday until 2 p.m. yesterday.

D.C. officials wrestled with a "washout" on 16th Street NW that tore apart the base of the road near Walter Reed Army Medical Center.

Floodwaters rising to four feet at the Silver Spring Metro station knocked out the automatic train control for the stretch of Red Line track between Glenmont and Silver Spring yesterday morning. That forced train operators to run the trains manually, which significantly reduced speeds, spokeswoman Lisa Farbstein said.

Metro workers spent the day pumping water from the flooded area and repairing or replacing electronic equipment.

Motorists unaware of the depth of the water on the roadways -- and how quickly it rose -- became stranded throughout the region Tuesday night.

"Usually, we see flash flooding in an isolated area," said Pete A. Piringer, spokesman for the Montgomery County Fire and Rescue Service. "But this was in three distinct areas all at the same time." Cars in Sligo Creek Park, Rock Creek Park and low-lying areas near the Potomac River were stranded. Rescue crews were busy from about 8:30 p.m. Tuesday until long after the rains stopped, and the water began to recede around midnight, he said.

Polikoff, 35, a 17-year firefighting veteran, knew that just six inches of floodwater is enough to knock a man off his feet. Two feet can, within seconds, send a car over a ditch or turn it upside down. He and his team members waded in water up to their waists to the first car, where two women sat huddled on the roof as the water rushed over the hood.

Once the women were fitted with life jackets and walked to safety, Polikoff and his team urged two other men, trapped in their cars with the water rising to their windows, to climb out. Standing in an eddy of slow-moving water, the firefighters hurled a 50-foot rope with a life ring and pulled the two men to safety, one at a time. The second man was rescued just as his car began to slide out from under him. It sailed across the road about 60 feet, Polikoff said.

His only thought, once all four were safe: No one was injured.

In fact, in numerous strandings and rescues throughout the region, few were hurt.

U.S. Park Police and D.C. fire crews rescued people in three vehicles trapped in floodwater between 10 and 10:30 p.m. A National Zoo police officer leaving work became trapped in his car in standing water that had overflowed from Rock Creek, D.C. fire department spokesman Alan Etter said.

Firefighters standing on the far bank of Rock Creek stretched a ladder to the car to form a bridge. One firefighter climbed across it and gave the man a flotation vest before bringing him out of the car.

Five family members, trapped in a vehicle heading north on Beach Drive just south of Porter Street, were saved when a Park Police officer waded through waist-high moving water to help them, said Sgt. Scott Fear, spokesman for the Park Police. About the same time, another Park Police officer spotted an elderly couple clinging to a stop sign as water rushed past them, Fear said. They had escaped their vehicle, which had become submerged on southbound Rock Creek Parkway.

Neal Dipasquale, a meteorologist at the National Weather Service's forecast office in Sterling, began issuing flash flood watches and warnings as the storm developed late Tuesday afternoon.

Rain and thunderstorms began forming and re-forming in the same area, lining up and moving from southwest to northeast through Virginia, the District and Maryland.

"We call it a training event," he said, "because all the storms act like a train. The first one sets up the pattern, and all the others line up and follow each other."

Tim Pfabe, 48, had been enjoying a steak and sushi dinner in Bethesda with his brother and high school buddy when the rain began to fall Tuesday evening. The three men, who vowed when they were students at Magruder High School that they would hike and camp in every national park in the United States, were poring over trail maps of the Grand Tetons in Wyoming, planning their upcoming trip.

The men delayed leaving the restaurant as they waited for the rain to stop. Finally, close to 10 p.m., they decided to leave. Pfabe drove his 1999 red Jeep Cherokee Sport, which has four-wheel drive.

As he rounded a bend on the darkened Kensington Parkway, Pfabe felt his vehicle pull. The puddle of water they had been driving through was now splashing up over the hood onto his windshield. His buddies urged him on. But once the swelling water covered the exhaust pipe, the car died. "I was really afraid of being stranded," he said. The men took off their pants and shoes and, in their underwear, pushed the Jeep out of the flood a few hundred yards to dry land.

Shortly before 3 p.m. yesterday, Pfabe returned to bail the water out and try to start his vehicle. Finally, with a reluctant splutter, it roared to life. Thick blue smoke splatted from the tailpipe.

"Next time," he said. "I'm going to back up and turn around."

Staff writers Lyndsey Layton, Amit R. Paley and Steven Ginsberg contributed to this report.

Emma Setchell of Australia and Ruari Markham and Clifford the dog, both of Takoma Park, watch the Sligo Creek Parkway cleanup. The footbridge to the Becca Lilly Playground could not withstand the surging water along Sligo Creek in Takoma Park during Tuesday night's heavy storms. Several motorists had to be rescued from their cars in Montgomery County.