The pile-up occurred on a road that had been wet with rain due to a tropical depression.
Eight of the deceased children were traveling in a van on its way to a home for abused and neglected youth.
Candice Gulley, the manager of the ranch, was the lone survivor of the van. She is in serious but stable condition in hospital.
Two of the children killed in the van were Mrs Gulley’s own children, aged four and 16.
They were returning to the ranch from a nearby beach and the van caught fire after the accident.
Michael Smith, general manager of the ranch, attended the scene of the accident on Saturday and said, “This is the worst tragedy I have ever been part of in my life.
“Words cannot explain what I saw. We love these girls like they are our own children. “
Cody Fox, 29, and his nine-month-old daughter were in another vehicle and were also killed.
Mr. Fox worked at his county’s emergency management agency and also ran a spa business with his father.
His colleague Aaron Sanders said: “He was a great guy and he will be sorely missed. He loved (his daughter) to die and that was his life. “
The crash happened about 35 miles south of Montgomery on Interstate 65 on Saturday, with authorities saying the vehicles most likely hydroplaned on wet roads.
A number of people were also injured and photos showed at least four vehicles set on fire, including two large trucks.
Sheriff Danny Bond wrote on Facebook: “Butler County has had one of the most terrible traffic accidents. I think it is the worst ever in our riding. “
The National Transportation Safety Board said it has sent 10 investigators to the area and that the local school, which was attended by most ranch residents, will have counselors available to students.
A GoFundMe account has been set up to help the ranch cover funeral costs, medical bills, and counseling for those affected.
In addition, in Tuscaloosa, about 100 km southwest of Birmingham, a 24-year-old man and a three-year-old boy were killed on Saturday when a tree fell on their house.
Tropical Depression Claudette had been classified as a storm when it arrived over the southeastern part of the United States in the early hours of Saturday.
It was downgraded to a tropical depression hours later, but still had enough power to trigger flood and storm warnings in parts of Georgia, South Carolina and North Carolina.
Heavy rain too whipped up Mississippi and Louisiana on Saturday.
Forecasters said it would revert to tropical storm status Monday over eastern North Carolina before moving into the Atlantic Ocean.