Rescuers to assess whether to continue search for children washed away in flash flood

Rescuers will assess Friday morning whether or not they can continue the search for a 2-year-old girl and her 9-month-old brother who were washed away with their mother in a flash flood in Bucks County, Pennsylvania, after severe weather on Wednesday halted efforts to find the children, officials said.

Search operations included K-9s from the Philadelphia Police Department and heavy equipment, the Upper Makefield Township Police Department wrote on Facebook, adding: "We will assess in the morning as to whether we can continue our search to bring Mattie and Conrad home."

As rescue crews on Thursday resumed the search for 2-year-old Matilda "Mattie" Sheils and her 9-month-old brother, Conrad Sheils, who have been missing since their family was caught in the deluge over the weekend while driving near Upper Makefield Township, President Joe Biden made his first public comments about five lives lost in the flash flood, including the missing children's mother.

"I want to say we’re praying for those who lost their lives in the flooding in Bucks County. The idea that there's not global warming, I think can't be denied by anybody anymore," Biden said during an event in Philadelphia to tout his economic agenda. "Anyway, we're grateful for the first responders who continue to look for a 2-year-old, Mattie, and her baby brother, Conrad. By the grace of God, maybe something will come of it."

Efforts to locate the children resumed Thursday morning after severe weather paused the search all day Wednesday.

"We are in the process of getting dog teams and having the dive unit check the conditions of the river to see if they can get into the water today," the Upper Makefield Township Police Department said in a statement released Thursday.

As of noon Thursday, K-9 teams from the Philadelphia Police Department were back searching the flood zone and heavy equipment had been brought in to help thoroughly comb through what police described as "extremely large debris piles," the Upper Makefield Police Department said in a statement.

Divers are prepared to enter a creek that spilled its banks during Saturday's flooding and the nearby Delaware River as soon as conditions allow them to commence an underwater search, police said.

"Unfortunately, we do not anticipate that occurring today," the police department said in its statement.

The children have been missing since Saturday afternoon when they and their family were caught in the flash flood while driving on Route 532 to a barbecue, authorities said.

The children's mother, 32-year-old Katie Seley, died after she grabbed Mattie and Conrad and tried to escape their vehicle but ended up being swept away in the violent weather event, officials said.

Seley was among five people killed in the storm. Her body was recovered on Sunday.

Rescue crews are expected to scale back the search after more than 100 emergency personnel scoured the flooded area along Hough's Creek between Saturday afternoon when the children and their mother were reported missing to Tuesday evening, Chief Tim Brewer of the Upper Makefield Fire Company said. He said crews have used cadaver dogs in ground searches of the creek's banks and have deployed sonar equipment and drones to search the creek, a tributary that leads to the Delaware River.

"We have searched the entire flood zone more than a dozen times," Brewer said at a news conference Tuesday afternoon, adding that the search covered roughly 117 acres.

Brewer said the focus of the search is switching to a "dive rescue operation."

"That will mean underwater assets mainly in the creek and we will work out from there. We still have K-9 assets in place, but we are going to begin to scale down," said Brewer, adding that crews have searched and re-searched the area.

"Tracking logs are over 160 miles, meaning we have backtracked several times," Brewer said.

The tragedy unfolded around 5:30 p.m. Saturday when more than 7 inches of rain fell within 45 minutes, causing Hough's Creek to spill its banks and generating a "wall of water" that took drivers on Route 532, also known as Washington Crossing Road, by surprise, Brewer said. He said 11 cars were washed away in the flash flood and at least one was found 1.5 miles from where it was swept into the creek.

The missing children and their family are from South Carolina and were in Pennsylvania visiting friends and relatives when disaster struck.

Mattie and Conrad's father, Jim Sheils, and their grandmother grabbed ahold of the missing siblings' 4-year-old brother and escaped their car as it and other vehicles were being washed away, according to officials. The father, grandmother and 4-year-old were found alive, officials said.

"They were caught in a flash flood," Brewer said. "The wall of water came to them, not the other way around."

Besides Katie Seley, four other people were confirmed dead in the Bucks County flooding. They were identified by the Bucks County Coroner's Office as Enzo Depiero, 78, and Linda Depiero, 74, both of Newtown Township, Pennsylvania; Susan Barnhardt, 53, of Titusville, New Jersey; and Yuko Love, 64, of Newtown Township.

The coroner's office said all of the victims died from drowning.

ABC News' Molly Nagle contributed to this report.