A management trainee and his wife were shot to death in the head and another man was critically wounded during a possible robbery at a Domino's Pizza, Police Chief James Gabbard said Wednesday.

The trainee, Bill Edwards, 27, and his wife, Frances, 29, a driver for the chain, were killed late Tuesday night, Gabbard said.Matthew Boornoosh, another Domino's employee, and the couple were each shot in the head in a back room, he said, adding that none of the victims was bound.

The Edwardses were the parents of a 2-year-old daughter, Tiffany, who was home with a baby sitter when they were killed.

"We're investigating robbery as the probable motive, but we don't have any conclusive evidence at this time," Gabbard said. Police have no witnesses, he added.

Police have been unable to interview Boornoosh, 27, who underwent emergency surgery and was listed in critical condition early Wednesday at Indian River Memorial Hospital.

An undisclosed amount of money was missing from the cash register, Gabbard said.