A Cook County Jail correctional officer is being fired after allegations he fatally shot a fellow motorist late last week outside of a Hammond, Ind. casino during what police said was a road rage incident, according to officials with the Cook County Sheriff's Office and the victim's family.Edgar Singleton Jr., 61, has been charged with the murder of Montrell Moss, 23, said sheriff's spokesman Ben Breit in an e-mail. Singleton became embroiled in a dispute with Moss on the evening of Thursday, Aug. 8 and allegedly discharged his weapon, resulting in the man's death, Breit said.The Cook County Sheriff's Office has de-deputized Mr. Singleton and is in the process of terminating his employment, according to Breit.The incident Thursday evening occured about 8 p.m. Thursday outside the Horsehoe Casino in Hammond, according to according to family members of Moss. They said Moss was driving to the Horseshoe Casino to have dinner. He was headed north on Indianapolis Boulevard with his girlfriend in the passenger seat and 3 boys, his son and her two sons, in the back seat.Police say that during the drive, the gold Chevrolet van Singleton was driving cut off the blue Buick LeSabre driven by Moss. Moss's girlfriend told WGN-TV that he threw a full cup of water from a fast food restaurant that hit the van.The driver of the van, later identified as Singleton, then pulled out a 9mm handgun and fired a single shot that shot Moss in the chest, family members and police said.Moss continued driving as his girlfriend gave him first aid, but the LeSabre crashed into a gasoline pump at a nearby gas station, shortly after, Hammond Police Chief Brian Miller said.Moss was pronounced dead at Franciscan St. Margaret Health hospital in Hammond a short while later. His girlfriend was not injured.Police said that while officers were interviewing witnesses at the crime scene, the gold Chevrolet van drove by and a witness identified the van and Singleton as the driver. Police pulled the van over, found the gun and a shell casing, and took the Singleton into custody.Singleton asked officers whether any weapon was found in Moss's vehicle but declined to give a statement, Miller said. The police chief said no weapon was found in the LeSabre.WGN-TV contributed to this report.