Three-buses were set on fire and a-few-others were vandalised by a mob after a motorcyclist was run over and killed by a speeding bus in Kolkata's Mominpur-area, police said. Two buses were racing against each other on Remount Road near the Kolkata Port Trust's gate no-13 when one of them knocked down motorcyclist identified Anil Verma, 32 before running over him, a senior-police-officer said.