The search continues for a 2-year-old girl and her 9-month-old brother who were swept away in ferocious flood waters that left their mother dead in southeastern Pennsylvania as a powerful storm hammered the region over the weekend.

The children and their family were visiting from South Carolina and were driving to a barbecue when they got stuck in flash flooding, Upper Makefield Fire Chief Tim Brewer said Sunday afternoon.

The family tried to escape the floodwaters, with the mother and grandmother grabbing the two children, while the father took a 4-year-old boy, Brewer said.

The father and young sibling “miraculously” made it to safety, he said. But the two women and young children were swept away by the flood waters.

The mother, who has not been identified, was found dead on Saturday, Brewer said. There was no sign of the two children.

The children’s grandmother survived and was treated at a local hospital, Upper Makefield Township Police said.

Search efforts will continue, Brewer said Sunday, adding that crews remain “steadfast on the commitment on finding and bringing these two children home.”

“We cannot even begin to imagine what the family is going through with two beautiful children gone,” Brewer said.

The children’s mother is among five people who died as storms battered Bucks County, Pennsylvania, Brewer said Sunday. Another seven people were still missing in flood waters, according to authorities.

“The mass casualty incident, like these, which we have never seen before, (is) unbelievable and devastating to all the families involved,” Brewer said.

Storms hit Southeastern Pennsylvania hard Saturday, bringing flash floods and inundating roadways less than a week after parts of the state were ravaged by storms.

Over the last month, parts of interior New England and the Northeast have seen 200% to 300% of their average monthly rainfall, leading to last week’s disastrous flooding event in parts of Vermont, New York and western Massachusetts.

Floods are among the deadliest weather hazards in the US, according to the weather service. It only takes 2 feet of rushing water to carry away most vehicles, including pickups and SUVs, the weather service says.

A flash flood can happen anywhere intense rain falls faster than the soil can absorb, and generally happen within a short time period after rain, making them more life threatening, according to the National Weather Service.

Search and rescue crews in Southeastern Pennsylvania are expected to see more favorable conditions Monday as the region gets a reprieve from the rain.

The threat of excessive rainfall decreases across the region Monday, with a marginal risk of excessive rainfall over parts of the Northeast to the Ohio Valley, according to the National Weather Service. There is a marginal risk for excessive rainfall for western Pennsylvania on Monday, as well as a marginal risk for severe storms, according to the Storm Prediction Center.

“Heavy rainfall across the Mid-Atlantic and Northeast will move off the coastline provide a well needed break to start the week,” the National Weather Service said. (CNN, excluding headline)

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