"Once we got there, the fog was kind of lifted at the scene," he said.
A total of 27 vehicles were involved in four separate accidents around 8:10 a.m., the Georgia State Patrol said in a news release.
They included six commercial vehicles and an empty petroleum tanker truck, which ruptured and caught fire, the patrol said.
Cobb said Wednesday morning that 12 people were taken to hospitals, most with what appeared to be minor injuries. However, the state patrol said later in the day that nine people were hurt. The discrepancy in the number of injuries could not immediately be resolved.
It wasn't known what caused the wrecks, but the area was under a dense fog advisory at the time, said Laura Belanger, a meteorologist at the National Weather Service in Peachtree City. In some areas, visibility was only a quarter-mile or less, Belanger said.
The pileup happened near Montrose, about 40 miles southeast of Macon. It shut down a roughly seven-mile stretch of the highway that is a major artery between Savannah and Macon, forcing cars to be detoured around the area.
Video from WMAZ-TV in Macon showed flames and dark, heavy smoke along the interstate.