Commerce, Georgia - A watermelon may have triggered the deadly shooting of a 6-year-old boy by his grandfather Sunday afternoon, according to police.

Robert L. Clark Jr., 55, shot and killed his 6-year-old grandson and wounded his wife before police shot him, according to Commerce Police Chief John Gaissert.

"At this point in the investigation we believe the argument precipitated over a watermelon," Gaissert said from the scene Monday. "The child either dropped the watermelon or cut it prematurely. The ensuing argument escalated and resulted in deadly violence."

The dead boy was identified as Michael Levigne. His 5-year-old brother was in the home at the time but escaped unhurt and now is in the custody of Family and Children Services.

Clark was shot by police after a 45-minute standoff when he opened the front door while brandishing a handgun. Two officers from Commerce, two from Jackson County, one from Pendergrass and a Georgia State Patrol trooper fired shots, police said.

"How many shots I can't tell you," said Gaissert, who said his officers are now on administrative leave.

Clark suffered multiple gunshot wounds. He and his wife, Linda Dale Clark, were air-lifted to Grady Memorial Hospital. The suspect is now at Atlanta Medical Center and in critical but stable condition, according to police. Mrs. Clark is in stable condition at Grady.

The GBI is leading the investigation because it involved a police shooting. It has charged Robert Clark with murder, aggravated assault and aggravated assault of a police officer.

There had been six or seven 911 calls from the residence in the past and DFACS has long been involved with the family, Gaissert said. He said the biological father, Andrew Levigne, has been busted on drug charges by Commerce police. Police had been unable to locate the boy's mother, Tawny Kitaen, as of Monday afternoon.

"I would characterize the family environment as dysfunctional," Gaissert said. "It was clearly a domestic violence incident."