Eight children were killed in a fiery multi-vehicle crash on a wet interstate that also killed a man and his baby in another vehicle, the most devastating blow from a tropical depression that claimed 13 lives in Alabama.

The crash happened on Saturday about 55 km south of Montgomery on Interstate 65 after vehicles likely hydroplaned on wet roads, said Butler County Coroner Wayne Garlock.

The van, containing children aged 4 to 17, belonged to the Tallapoosa County Girls Ranch, a youth home operated by the Alabama Sheriffs Association.

Michael Smith, the youth ranches CEO, said the van was heading back to the ranch near Camp Hill, northeast of Montgomery, after a week at the beach in Gulf Shores.

It caught fire after the wreck and Candice Gulley, the ranch director, was the van’s only survivor – pulled from the flames by a bystander.

Gulley remained hospitalised on Sunday in Montgomery in serious but stable condition. “She’s going to survive her physical injuries,” Smith said. Two of the dead in the van were Gulley’s children, aged 4 and 16. Four others were ranch residents and two were guests, Smith said.

“This is the worst tragedy I’ve been a part of in my life,” said Smith.

“We love these girls like they’re our own children.”

The crash also claimed the lives of two other people who were in a separate vehicle. Garlock identified them as 29-year-old Cody Fox and his 9-month-old daughter, Ariana, both of Marion County, Tennessee.

“He was a great guy and we’re really gonna miss him,” said Aaron Sanders.

Multiple people were also injured.

The National Transportation Safety Board tweeted that it was sending 10 investigators to the area on Sunday to investigate the crash, photos of which showed at least four burned vehicles, including two large trucks.

It said the inquiry would focus on vehicle technologies such as forward collision warning systems, fuel tank integrity and occupant survivability.

Meanwhile, a 24-year-old man and a 3-year-old boy were also killed on Saturday when a tree fell on their house just outside the Tuscaloosa city limits, said Capt. Jack Kennedy of the Tuscaloosa Violent Crimes Unit.

Makayla Ross, a 23-year-old Fort Payne woman, died on Saturday after her car ran off the road into a swollen creek, DeKalb County Deputy Coroner Chris Thacker said.

The deaths occurred as drenching rains from Tropical Depression Claudette pelted northern Alabama and Georgia late Saturday. As much as 12 inches of rain was reported earlier along the Mississippi Gulf Coast.

Flash flood watches were posted on Sunday for eastern Georgia, the southern two-thirds of South Carolina and the North Carolina coast. A tropical storm watch was issued from South Santee River, South Carolina, to the Little River Inlet, forecasters said.

Garlock said the location of the multi-vehicle wreck is “notorious” for hydroplaning, as the northbound highway curves down a hill to a small creek.

The Tallapoosa County school system said counselors would be available on Sunday at the 225-student Reeltown High School, where some of the ranch residents were students. Smith said the ranch, which is Christian-based, would likely have a memorial service later, asking for prayers as he began to cry.

Gulley had worked with children for years, beginning when she and her husband were house parents at the ranch for seven years.

“My heart goes out to the loved ones of all who perished,” Alabama Gov. Kay Ivey said in a statement.

Aside from rainy weather, it seemed to be business as usual along North Carolina’s Outer Banks on Sunday.