COVINGTON, Ga. — Fire officials say they know a fire that caused heavy damage to a popular Covington restaurant in early March began in the kitchen but private investigators have taken over the probe.

Bangkok Grill at 5135 Hwy. 278 has been closed since a March 6 fire at the longtime Covington business.

Four fire units responded to the 10:42 p.m. report of a fire at the Thai restaurant and found an ongoing blaze, said Covington Fire Marshal Joe Doss.

He said city investigators have determined the fire began in the kitchen area. However, the cause of the fire is listed as “undetermined” because the probe has been turned over to investigators working for an attorney, Doss said.

“Our investigation … we have an origin, a location, but the cause is going to be ‘undetermined’ because the private investigators are taking that over. It’s in their hands right now,” Doss said.

The restaurant, which specializes in geniune Thai cuisine, is located on the south side of U.S. 278 near the highway’s I-20 interchange. It opened in 2009.

The restaurant’s owners did not return a call for comment.