The protesters demanded the arrest of the driver and conductor of the public Lahore Transport Co. bus.
Tabish Aslam, 18, who was standing on the footstep of the bus, fell when the driver closed the door. He died at the scene of the accident in the Dharampura area, witnesses said.
Aslam had boarded the bus to get to the Technical Training College, Gulberg, where he was in his fourth year.
The bus driver and conductor escaped.
Protesters blocked a road, leading to temporary backups.
Police took into custody five students on arson and violence charges, students said.