Al-Qaeda and Taliban fighters have carried out scores of attacks in Pakistan, usually targeting security forces
Police in Pakistan have arrested a man over a car bombing that killed at least 25 people in the eastern Pakistani city of Faisalabad.
The bomb went off on Tuesday outside a gas station in a neighbourhood full of government buildings including police offices, and it severely damaged an office of Pakistan's state-run airline as well as a local gas station.
Scores of people were wounded in the explosion, and many remain trapped under the rubble, authorities said.
Officials say the arrested man may also have been involved in a 2009 attack on a Sri Lankan cricket team.
"It was a car bomb blast. The explosive was planted in a car. We are investigating whether a suicide bomber was involved or not," police chief Aftab Cheema told the AFP news agency.
Pakistani television stations showed piles of bricks and chunks of twisted metal from cars, strewn across the wrecked gas station.
'Target carefully chosen'
The Pakistani Taliban claimed responsibility for the deadly attack.
Ahsanullah Ahsan, Taliban spokesman, said the target of the blast was an office of Pakistan's Inter-Services Intelligence (ISI).
Ahsan said the blast was carried out to avenge the killing of a Taliban fighter by security forces in Faisalabad last year.
Al Jazeera's Kamal Hyder, reporting from the Pakistani capital, Islamabad, said Faisalabad has seen attacks in the past.
But the city, a key hub for Pakistan's textile industry, has rarely been targeted. However, it lies in Punjab province, where armed religious groups are believed to be growing in strength.
Our correspondent said security forces are searching for clues behind the blast and have cordoned off the gas station area.
"The police are saying that this was indeed a bomb. They have no evidence that this was a suicide attack. But they say the device appears to have been planted in a vehicle close to that compressed natural gas station and therefore the explosion wreaked havoc, because the pump itself blew up," he said.
"There was quite a bit of opposition to the fact that this station should not have been there in the first place, but the station was allowed to function in a highly sensitive area.
"And there was of course apprehension that in case of an accident, it would pose a threat, so the target [was] obviously very carefully chosen."