A KMB bus was damaged yesterday when a gas explosion launched a metal drain cover into the air, hitting the vehicle. The bus was hit at the junction of Ngau Tau Kok Road and Horse Shoe Lane in Sau Mau Ping at 8.30am. The driver inspected the bus after he heard a loud noise. One of the windows was broken. An investigation indicated the explosion was caused by methane gas. No one was injured. Towngas sent staff to investigate.