A sport utility vehicle speeding down a muddy road slammed into trees and exploded, killing four people, including two children, and injuring two others, authorities said.

Investigators believe alcohol, recent rain and reckless driving may have been factors in Friday night's crash of the Ford Bronco, which burned completely, state Trooper J.T. McMillan said.

"They were out there, playing around, mud-bogging on the dirt road," McMillan said. "They got stuck in the dirt and were pulled out by a dump truck. They sped off down the road and the driver struck two trees."

The SUV was traveling around 70 mph at impact, and the occupants weren't wearing seat belts, he said.

The Georgia State Patrol had not released the victims' names but identified them as a 24-year-old woman who was driving, a 36-year-old woman, a 2-year-old boy and a 4-year-old girl. The children were riding in the back seat.

A 36-year-old woman and a 4-year-old boy were being treated at the Atlanta Medical Center, but their conditions were not available Saturday.

Griffin is about 37 miles south of Atlanta.