KARACHI/ISLAMABAD－At least 17 people were killed and 16 others injured in an explosion on the ground floor of a two-story building in Pakistan's southern port city of Karachi on Saturday, The Associated Press reported.

Several people were feared to be trapped under rubble. Initially, 12 people were reported dead and 11 others injured in Saturday's gas explosion in a sewage system in the commercial hub of Pakistan, but some critically injured people died overnight and on Sunday.

The blast was apparently caused when something ignited gas that had accumulated in the sewer beneath a local bank building in the Shershah neighborhood of the city, police spokesman Sohail Jokhio said.

Video footage aired on local television showed that the entire structure of the building in which the Shershah branch of HBL bank is located had been badly damaged. The floor was blown out and furniture was mired in sewage from below. The impact of the blast damaged several cars parked nearby and threw debris onto a petrol station on the other side of the building.

Jokhio said it was unclear what ignited the gas but a team of explosives experts had been summoned to investigate.

Mohammad Sameer, a witness, said he was in the crowded bank branch moments before the blast but left shortly before the explosion. He rushed back to the damaged bank to rescue victims, he said. "Thank God I left the venue."

Many sewage channels in the city have been covered, mostly illegally, by concrete structures.

Rescue efforts

Mukhtar Abro, a local administrator, said illegal construction over the sewage area of the explosion was due to be demolished.

Rescue teams called in heavy machinery to remove the debris to look for anyone trapped.

Karachi is the provincial capital of Sindh. Sindh Chief Minister Syed Murad Ali Shah expressed sorrow over the accident and directed police to investigate the possibility of terrorism.

In the evening, a bomb apparently planted in a motorcycle parked in a bazaar exploded in the city of Quetta in Pakistan's southwest Balochistan Province, killing a passerby and wounding four others, police said.

Three women and seven men were injured in the explosion, the Balochistan Health Department said.

The blast was the result of an improvised explosive device fixed inside a motorcycle parked in the market, the rescue department of the nongovernmental organization Edhi Foundation in Quetta told Xinhua.

No group had claimed responsibility for the attack.

On Sunday, a bomb blast hit a vehicle in Bajaur district of Pakistan's northwest Khyber Pakhtunkhwa Province, killing at least two people and injuring five others, police and local media said.

Agencies - Xinhua