Months worth of heavy rain fell in a matter of hours on Texas Hill Country, killing at least 13 people and leaving more than 20 girls attending a summer camp unaccounted for Friday as search teams conducted boat and helicopter rescues in the fast-moving flood water.

Desperate pleas peppered social media as loved ones sought any information available about people caught in the flood zone.

Lt. Gov. Dan Patrick said somewhere between 6 and 10 bodies had been found so far in the frantic search for victims. Meanwhile, during a news conference conducted at the same time as Patrick’s update, Kerr County Sheriff Larry Leitha reported that there were 13 deaths from the flooding.

At least 25cm of rain poured down overnight in central Kerr County, causing flash flooding of the Guadalupe River and leading to desperate pleas for information about the missing.

“Some are adults, some are children,” Patrick said during a news conference. “Again, we don’t know where those bodies came from.”

Teams conducted dozens of rescues, and emergency responders continued to search for those who were unaccounted for. That includes more than 20 girls missing from summer camps.

“I’m asking the people of Texas, do some serious praying this afternoon. On-your-knees kind of praying, that we find these young girls,” Patrick said.

Comments on a Facebook post from the Kerr County sheriff’s office were riddled with photos of people in the flood zone. Loved ones posted there, hoping someone could offer an update on the whereabouts of those they hadn’t heard from. One woman said she couldn’t reach her daughter, who had rented a cabin in Hunt for her husband and two children, and pleaded for someone to post the names of those already evacuated.

Judge Rob Kelly, the chief elected official in the county, confirmed fatalities from the flooding and dozens of water rescues so far. He said he was advised not to cite specific numbers and said authorities are still working to identify those whose lives were lost.

“Most of them, we don’t know who they are,” Kelly said during a news conference. “One of them was completely naked, he didn’t have any ID on him at all. We’re trying to get the identity of these folks, but we don’t have it yet.”

One family survives a terrifying ordeal

Erin Burgess’ home sits directly across from the river in the Bumble Bee Hills neighborhood, west of Ingram. When she woke up to thunder at 3:30 a.m. Friday morning, “it was raining pretty heavy, but no big deal,” she said.

Just 20 minutes later, Burgess said water was coming in through the walls and rushing through the front and back doors. She described an agonizing hour clinging to a tree and waiting for the water to recede enough that they were able to walk up the hill to a neighbor’s.

“My son and I floated to a tree where we hung onto it, and my boyfriend and my dog floated away. He was lost for a while, but we found them,” she said, becoming emotional.

Of her 19-year-old son, Burgess said: “Thankfully he’s over 6 feet tall. That’s the only thing that saved me, was hanging on to him.”

A flood watch issued Thursday afternoon estimated isolated amounts up to 17cm of rising water. That shifted to a flood warning for at least 30,000 people overnight.

When asked about the suddenness of the flash flooding, Kelly said “we do not have a warning system” and that “we didn’t know this flood was coming,” even as local reporters pointed to the warnings and pushed him for answers about why more precautions weren’t taken.

“Rest assured, no one knew this kind of flood was coming,” he said. “We have floods all the time. This is the most dangerous river valley in the United States.”

Texas Gov. Greg Abbott said the state was providing resources to Hill Country communities dealing with the flooding, including in Kerrville, Ingram and Hunt.

The Texas Hill Country, a scenic and rocky gateway to booming vineyards and vacation rentals, begins west of the state capital and is a popular outdoor summer getaway. Parts of the region are prone to flash flooding.

Dozens of people posted on Facebook asking for any information on their children, nieces and nephews attending one of the many camps in the area, or family members that went camping during the holiday weekend.

Ingram Fire Department posted a photo of a statement from Camp Mystic, saying the private Christian summer camp for girls experienced “catastrophic level floods.” Parents with a daughter not accounted for were directly contacted, the camp said.

Two other camps on the river, Camp Waldemar and Camp La Junta, said in Instagram posts that all there were safe.

The Guadalupe’s river gauge at the unincorporated community of Hunt, where the river forks, recorded a 6.7m in just about two hours, according to Bob Fogarty, meteorologist with the National Weather Service’s Austin/San Antonio office. Fogarty said the gauge failed after recording a level of nine metres.

“This is the kind of thing that will catch you unaware,” Fogarty said. “The water’s moving so fast, you’re not going to recognize how bad it is until it’s on top of you.”

Areas east along the Guadalupe River were preparing for their own flooding as the rapid waters rushed downstream from Hunt and Kerrville. In Kendall County, home to the unincorporated community of Comfort, the sheriff’s office sounded the alarm.

“We regret to inform everyone that the flood situation in Comfort is not improving,” the post read. “We have sounded the flood sirens and urge all residents in low-lying areas of town to evacuate immediately.”

New Jersey also sees deaths due to severe weather

Meanwhile, strong thunderstorms were being blamed for at least three deaths in central New Jersey, including two men in Plainfield who died after a tree fell onto a vehicle they were traveling in during the height of a storm there, according to a city Facebook post.

The men were ages 79 and 25, officials said. They were not immediately publicly identified.

“Our hearts are heavy today,” Mayor Adrian O. Mapp said in a statement. “This tragedy is a sobering reminder of the power of nature and the fragility of life.”

The city canceled its planned July Fourth parade, concert and fireworks show. Mapp said the “devastating” storms had left “deep scars and widespread damage” in the community of more than 54,000 people and it was a time to “regroup and focus all of our energy on recovery.”

Continuing power outages and downed trees were reported Friday throughout southern New England, where some communities received large amounts of hail. There were reports of cars skidding off the road in northeastern Connecticut.