Lake Butler, Fla. ? Seven children who had been adopted by a single family were killed Wednesday in a fiery crash when their car was crushed between a truck and a stopped school bus in rural northern Florida.

The children, ranging in age from 15 years to 21 months, were headed toward their home about two miles north of the crash site. The truck hit them from behind, pushing their car into the bus and causing the car to burst into flames, police said.

Everyone in the car was killed, including the 15-year-old girl who was driving illegally. All of the youngsters had been adopted by the same family and lived together, police said.

It was unclear why the children were unaccompanied.

Evidence from the scene showed that the truck, which was carrying bottled water, did not brake before hitting the car on the two-lane road, said Lt. Mike Burroughs of the Florida Highway Patrol.

Police investigate an accident scene involving a school bus, car and semi truck Wednesday near Lake Butler, Fla. Seven adopted children were killed in the crash, which occurred when the truck hit the car from behind and pushed it into the bus, police said.

The bus ended up 200 feet from where the car struck it, and the cab of the truck lay overturned near the scene, Burroughs said. The bus was at an approved bus stop.

“It’s a very chaotic scene,” Burroughs said. “It’s just a mangled, charred mess.”

Nine students were on the bus, and three were thrown from the vehicle by the force of the crash. But the extent of their injuries was unclear.

The car was driven by 15-year-old Nicki Mann, who was with siblings Elizabeth Mann, 15; Johnny Mann, 13; Heaven Mann, 3; Ashley Kenn, 13; Miranda Finn, who was either 8 or 9 years old; and Anthony Lamb, who was almost 2 years old. Lamb was in the process of being adopted, Burroughs said.