A traffic stop early Sunday led to the discovery of a loaded handgun that might have recently been fired, according to Massachusetts State Police. A State Police trooper stopped a gold Honda Accord at about 2 a.m. Sunday for failing to stop at a red light on Resnic Boulevard in Holyoke. The trooper noticed the barrel of a gun peeking out from under the thigh of the front-seat passenger. The driver sped off and crashed, and when the trooper caught up, the driver and two passengers were not in the car, police said. The trooper and a Holyoke police officer found a loaded 9-millimeter handgun and several used casings, which the officers described as having “the fresh scent of being recently fired,” according to State Police.