At least six people were killed and 20 others injured when a passenger van hit a bus in Pakistan's east Wazirabad district on Tuesday, the media reported.The accident happened when the van carrying about 20 people collided with the bus at a roundabout in the district located in the east Punjab province, Geo News said.The ill-fated van was on its way to north Rawalpindi district when it met the accident.Police says the accident happened due to over speeding of the van driver who lost control over the vehicle while negotiating a turn at the roundabout.The van had a head-on collision with the bus and the van driver was also among the killed people.The injured people have been shifted to a nearby hospital.