An explosion at a bus terminal in Pakistani city Multan has left at least 10 people dead and injured 57 others, officials said on Monday. It's unclear what caused the blast, which happened when a motorcycle collided with a motorized rickshaw. Local media reports quoted officials as saying that one of the vehicles appeared to have been carrying a bomb, but one official said the bomb was remotely detonated. Ball bearings were found at the scene, but forensic teams are still investigating. No group has claimed responsibility for the attack. Pakistani Prime Minister Nawaz Sharif expressed his grief for the victims and called for rescue agencies to provide special medical care to those injured.