The sheriff said it wasn't raining and there was no ice on the road. "This accident is not weather related at all," he said.
Divers from the Philadelphia fire department had to be called to find the submerged vehicle. Prince said the vehicle was pulled from the water after 3 a.m. In addition to the 30 emergency workers, about 20 Choctaw tribal members gathered at the site, he said.
"It looked like he has just run off the road and went into the water," Prince said. "It was deep and swift. The vehicle was completely submerged."
Waddell said the bodies have been sent to Jackson for autopsies. The Mississippi Highway Patrol will reconstruct the accident starting Sunday to learn more.
Tribal spokeswoman Misty Dreifuss said funeral arrangements would likely be made Sunday. She said the children are expected to be buried together. Dreifuss said word of the deaths spread quickly through the 10,000-member tribe and that members "definitely have been hit pretty hard."
Waddell said that he can't recall a deadlier accident in the county in his 26 years of law enforcement.
Follow Jeff Amy at: http://twitter.com/jeffamy