Eight of the victims, aged between 4 and 17, were aboard a van from the Tallapoosa County Girls Ranch, a youth home for abused or neglected children.
The only survivor of the van was the driver, the Ranch's director Candice Gulley, who was pulled unconscious from the flaming wreck by a bystander; the witness tried to go back and save the children, but it was too late.
Gulley was rushed to hospital in a serious but stable condition.
Among those killed in her van were her own two children, aged four and 16, Ranch CEO Michael Smith told AP. Four more of the victims were ranch residents, and two more were guests.
Smith was driving a second van full of children back to the ranch, as they both returned after a week's vacation at the beach in Gulf Shores. The second van was not immediately aware of the crash.
"This is the worst tragedy I've been a part of in my life," Smith said after returning to the site of the crash later in the day. "Words cannot explain what I saw... We love these girls like they're our own children."
He said Gulley was going to survive "her physical injuries."
Also killed in the crash in a separate car was 29-year-old firefighter Cody Fox and his 9-month-old daughter Ariana Fox.
Cody died at the scene, while the baby died later at hospital. Cody's fiancée Hayle Anderson was injured, but is expected to survive.
The accident brings Tropical Depression Claudette's one-day death toll to 13: that same day, a 24-year-old man and a three-year-old boy were killed when a tree fell on their house near Tuscaloosa, while a 23-year-old Fort Payne woman died when her car ran off the road into a swollen creek.