An explosion ripped through a minibus traveling in northwestern Pakistan on Monday, killing 18 people, police said. The explosion tore apart the vehicle, killing all 17 people on board, and tipped over a second bus nearby, said Hangu police chief Abdur Rasheed. One person on the bus that tipped over was killed and 11 others were wounded, he was quoted as saying by the Associated Press. Rasheed said the blast occurred when the gas cylinder on board malfunctioned.