Eight children travelling in a van were killed in a multi-vehicle crash on a wet interstate highway in Alabama, in the southern US.
A man and his baby daughter in another vehicle were also killed in the accident on Saturday.
It was the most devastating blow from a tropical depression that claimed 13 lives as it caused flash floods and brought tornadoes that destroyed dozens of homes.
The crash happened about 2.45pm local time, 55 kilometres south of state capital Montgomery, on Interstate 65.
Vehicles likely hydroplaned on wet roads, Butler County coroner Wayne Garlock said.
According to reports, around 18 vehicles were involved in the pile up.
The van, containing children aged 4 to 17, belonged to the Tallapoosa County Girls Ranch, a home for juveniles operated by the Alabama Sheriffs Association.
Michael Smith, the youth ranches chief executive, said the van was heading back to the ranch near Camp Hill, north-east of Montgomery, after a week at the beach in Gulf Shores, a city on Alabama's Gulf Coast.
The vehicle caught fire after the collision and ranch director Candice Gulley was the only survivor.
She was pulled from the flames by a bystander.
Ms Gulley remained in hospital in Montgomery on Sunday, in a serious but stable condition.
“She’s going to survive her physical injuries,” Mr Smith said.
Two of the dead in the van were Ms Gulley’s children, aged 4 and 16. Four of the other children who were killed were ranch residents and two were guests, Mr Smith said.
“This is the worst tragedy I’ve been a part of in my life,” he said.
He returned to the ranch on Sunday to console residents who had returned from Gulf Shores in a separate van and did not see the accident.
“Words cannot explain what I saw,” Mr Smith said of the accident site, which he visited Saturday.
“We love these girls like they’re our own children.”
The crash also killed two other people in a separate vehicle. Mr Garlock identified them as 29-year-old Cody Fox and his nine-month-old daughter, Ariana, both of Marion County, Tennessee.
A number of people were also injured, said officials.
The US National Transportation Safety Board said it was sending 10 investigators to the area to investigate the crash.
Photos showed at least four burnt vehicles, including two large trucks.
The board said the inquiry would focus on vehicle technologies, such as forward-collision warning systems, fuel tank integrity and occupant survivability.
Meanwhile, a man aged 24 and a boy of 3 were also killed Saturday when a tree fell on their house just outside the Tuscaloosa city limits, said Capt Jack Kennedy of the Tuscaloosa Violent Crimes Unit.
A woman, named as Makayla Ross, 23, died on Saturday after her car ran off the road into a swollen creek.
The deaths occurred as rains from Tropical Depression Claudette deluged northern Alabama and Georgia late Saturday. As much as 30 centimetres of rain was reported earlier from Claudette along the Mississippi Gulf Coast.
Flash flood watches were posted Sunday for eastern Georgia, the southern two-thirds of South Carolina and the North Carolina coast.
A tropical storm warning was in effect in North Carolina from the Little River Inlet to the town of Duck on the Outer Banks.
A tropical storm watch was issued from South Santee River, South Carolina, to the Little River Inlet, forecasters said.
The Tallapoosa County school system said counsellors would be available Sunday at the 225-student Reeltown High School, where some of the ranch residents were students.
Mr Smith said the ranch, which is Christian-based, would likely have a memorial service later.
Claudette re-strengthened late Sunday, with the National Hurricane Centre reporting top winds at 55 kilometres an hour.
The depression was expected to return to tropical storm status Monday over eastern North Carolina before heading out to the Atlantic Ocean.