Four people were killed Friday night in a head-on collision on Short Mountain Road, deaths investigators believe could have been prevented if any of the victims had been wearing a seatbelt.Fatally injured was Cynthia Womack, 31, who was the driver and lone passenger in her 2005 Nissan Altima. Also fatally injured was Greg Jones, 37, who was driving a 2008 Chevy pickup that collided with Womack. His passengers, Steven Bush, 49, and Darrell Evans, 49, were also dead at the scene.According to Highway Patrolman Donnie Clark, the wreck happened at 7:30 p.m. on Short Mountain Road near its intersection with Merry Oaks Road.