A passenger bus skidded off a mountain road and plunged into a deep ravine in heavy rain in southwestern Pakistan on Sunday, killing 19 people and injuring 12 others, a government official said. Mahtab Shah, assistant district commander of Sirani district in Balochistan province, said the bus was carrying about 35 passengers traveling from the capital Islamabad to the city of Quetta. The death toll is expected to rise as many of the injured are in critical condition. He said rescue teams were searching for survivors in the wreckage of the damaged vehicle and in the outskirts bordering Khyber Pakhtunkhwa province. Shah said the bus apparently skidded on the wet road amid heavy rain and the driver lost control of the vehicle, which plunged about 200 feet (61 meters) into the ravine. At least 22 people died when a minibus fell into a ravine in Balochistan last month.