The incident occurred about 2:45 p.m. Sunday at 191 E. John Sims Parkway.
The two men got into a physical altercation in the restaurant s parking lot, according to the Facebook post. One of the men pulled out a firearm, and the other man grabbed the barrel of the gun and attempted to pull it away.
The weapon went off during the struggle, wounding both individuals, the post said.
Both men were transported to the Fort Walton Beach Medical Center for medical treatment.
The Niceville Police Department has identified the men but has not publicly released their names or the extent of their injuries.