A short circuit caused a bus battery to explode in Khushab, wounding 19 passengers, two of them seriously, police said on Tuesday.
The blast occurred late Monday, just after the bus left the eastern town of Khushab for a nearby city, area police officer Ameer Abbas said.
The driver alerted passengers after he saw smoke near the engine, but the battery exploded as he was trying to park, injuring 19 of the 29 on board.
The injured were taken to a hospital, where two were stated to be in a critical condition.