At least four people were killed and 30 others injured when a passenger bus turned turtle due to over speeding here on Wednesday. Rescue sources said that a driver of a reckless driven passenger bus lost control on steering of the vehicle and it over turned in Mananwala area of Sheikhupura. Four people were killed on the spot in the accident while 30 others were injured. Bus driver fled the scene. The bodies and injured were shifted to hospital where condition of some wounded people was stated to be critical. The police impounded the bus and after registering a case against the driver have started an investigation.