WASHINGTON CROSSING, Pennsylvania (AP) — Heavy rains pounded and already saturated the United States Northeast on Sunday for the second time in a week, spurring another round of flash flooding, cancelled airline flights and power outages. In Pennsylvania, a sudden flash flood late Saturday afternoon claimed at least five lives.

Officials in Bucks County’s Upper Makefield Township in Pennsylvania said torrential rains occurred around 5:30 pm Saturday in the Washington Crossing area, sweeping away several cars. At least five people died and two children, a nine-month-old boy and his two-year-old sister, remained missing, authorities said.

Other parts of the East Coast were experiencing heavy rain, including Vermont. Authorities there said landslides could become a problem Sunday as the state copes with more rain following days of flooding.

“There are flash flood warnings throughout the state today. Remain vigilant and be prepared,” Vermont Governor Phil Scott said.

Sunday’s strong storms led to hundreds of flight cancellations at airports in the New York City area, according to the tracking service FlightAware. More than 350 flights were cancelled at Newark Liberty International Airport in New Jersey alone, while more than 280 flights were cancelled at Kennedy International Airport in New York. Hundreds of flights were delayed.

The National Weather Service issued flash flood warnings and tornado watches for parts of Connecticut, western Massachusetts, Vermont and New Hampshire. A tornado warning was issued for an area along the Massachusetts-New Hampshire border.

Thousands of power outages also were reported.

New York Governor Kathy Hochul urged people to stay home Sunday until the storms passed.

“Here comes the rain. It just seems unrelenting this year,” she said. “You have to avoid unnecessary travel. … A flash flood doesn’t give you warning … and in those moments your car can go from a place of safety to a place of death.”

Hochul said five inches (13 centimetres) of rain fell within two hours in Suffolk County on Long Island. The state saw $50 million in damages from last week’s storms. Disaster declarations will cover more than a dozen New York counties.

Manchester, New Hampshire, the largest city in northern New England, opened its emergency operations centre in response to severe weather. Manchester Mayor Joyce Craig and other officials urged residents to stay inside.

Flooding forced Tweed New Haven Airport in Connecticut to close Sunday. The small airport, which offers daily commercial flights from one carrier, Avelo Airlines, said in a Twitter post that the terminal was closed until further notice. Several flights were delayed.

Flash flooding was reported in New Haven, Hartford, Waterbury and other Connecticut towns, leaving many roads impassable. Connecticut Governor Ned Lamont said he was headed to Bristol, home of ESPN, to view flooding.

In northern New Jersey, some roads were closed Sunday as crews worked to repair stretches of concrete that buckled under heavy rain and flooding. Local creeks washed over passageways and a rockslide blocked Route 46. Thoroughfares were a mess of water and rocks covered in brown sludge.

In Pennsylvania, a sudden, torrential downpour turned deadly in Upper Makefield Township.

Fire Chief Tim Brewer told reporters the area got about 6 1/2 to seven inches of rain (about 18 centimetres) in 45 minutes.

“In my 44 years, I’ve never seen anything like it,” he said. “When the water came up, it came up very swiftly.”

About four to five feet of water washed over the road and three of an estimated 11 cars were swept away. All three were later recovered and no one was found inside, Brewer said. Eight people were rescued from the cars and two from the creek, he said.

The two children who remained missing Sunday are part of a Charleston, South Carolina, family visiting family and friends. They were on their way to a barbecue when their vehicle got stuck in the flash flood, Brewer said.

“As they tried to escape the fierce floodwaters, Dad took his 4-year-old son while the mother and the grandmother grabbed the two additional children, aged nine months and two years,” he said. The father and son were “miraculously” able to get to safety. “However the grandmother, the mother, and the two children were swept away by the floodwaters,” Brewer said. The mother was among those later found dead.

“We continue to look for the two children. We are not going to give up,” Brewer said.

About 150 people were searching the creek during the night and 100 were involved Sunday. Brewer said earlier that officials were treating the effort as a rescue “but we are fairly certain we are in a recovery mode at this time.”

Governor Josh Shapiro vowed aid from state emergency and transportation officials.

“All hands are on deck,” Shapiro said.

As far south as North Carolina, floodwaters were blamed on the death of a 49-year-old woman whose car was swept off a road in Alexander County late Saturday night. A man who was in the car with her was rescued.

Meanwhile, recovery efforts were underway in Vermont from recent days of heavy precipitation.

The Vermont Agency of Transportation said 12 state roads remained closed while 12 were partially open to one lane of traffic and 87 have been reopened that were previously closed.

The agency said 211 bridge inspections have been completed this week in damaged areas and there are four state bridges closed and four town structures closed.

Rail lines throughout Vermont were also damaged, the transportation agency said. The agency said it reopened 57 miles (92 kilometres) of rail lines, and 64 miles of rail line remained closed.

“Our crews have been working tirelessly all week to repair the damaged state roads and bridges, and to restore the state’s transportation infrastructure for Vermonters and visitors,” Transportation Secretary Joe Flynn said.

Heavy precipitation was not the only extreme weather plaguing the US A scorching heat wave across the Southwest has put roughly one-third of Americans under some type of heat watch or warning. That included brutal temperatures in the hottest place on Earth — Death Valley, which runs along part of central California’s border with Nevada. Las Vegas also faced the possibility of reaching an all-time record temperature Sunday.

The US Environmental Protection Agency posted air quality alerts for several states stretching from Montana to Ohio on Sunday because of smoke blowing in from Canadian wildfires. Hochul, the New York governor, said she expected air quality alerts to be issued for northern and western parts of New York state Monday because of the wildfires.

“Air Quality alerts are in place for much of the Great Lakes, Midwest, and northern High Plains,” the National Weather Service said. “This is due to the lingering thick concentration of Canadian wildfire smoke over these regions.”