Staff at a Hamilton electronics store had the scare of their life yesterday when an empty bus rolled into their front window.While it is unclear exactly how the accident occurred, it appears that the bus was parked at the Hamilton Bus Terminal when it rolled backwards, directly into Audio Visual Electronics Ltd, on Washington Street South on the opposite side of the road.One shopkeeper said the collision shook him, but he became even more frightened when the damaged bus began to release a cloud of smoke.“I had no idea what was going on,” he said. “Then I started to see smoke coming out of it. At that point I wanted to run [away from the window], but there was nowhere to go.”While no one was injured in the accident, the storefront was severely damaged, with the front window shattered and the lower portion of the wooden door bent inward by the vehicle's bumper.Even as staff cleaned up glass from inside the store, business continued with customers coming inside to collect repaired phones.The bus was also damaged in the crash, leaving a large puddle of oil and antifreeze outside the store which Corporation of Hamilton staff covered with industrial absorber.One witness compared the sound of the crash to a gun shot, while another said the impact shook the entire building.“I thought it might have been backing up but it never slowed down. It just got faster and faster,” one woman said.“Thank God there was nobody behind it. They would have been crushed.”A spokesman for the Public Transportation Department said yesterday that the cause of the accident was being investigated.“The bus rolled back from its parked position and hit a store window,” the spokesman said.“Department of Public Transportation Supervisors and an Assistant Manager attended the scene of the accident and an investigation has been initiated to determine the cause and extent of damage. There were no injuries reported.”