Firefighters suspect a gas leak might be to blame but that could not be confirmed by late Sunday.
No one was injured although several firefighters were being treated for heat. The restaurant was open for lunch on Sunday but was closed when the incident occurred.
The explosion occurred around 6 p.m. and the blaze was still burning around 8 p.m. Eyewitnesses said the rear of the building and some of the roof was blown off. It is located at 212 N. Main St. in Adairsville.
Sharon Southerland, who co-owns the restaurant with her husband Jim, said the eatery opened three years ago.