A huge bomb explosion ripped through a multi-storey building housing international businesses in the southern Pakistani port of Karachi yesterday, killing two people and injuring four others, police said.
"It was a bomb explosion and the device was placed near a pillar at the entrance to the 12-story plaza," police officer Ajmal Magsi said.
Two people were killed, he said, adding that four others were injured by flying shards of glass. "None of them was seriously wounded."
Police chief of operations in Karachi Tariq Jamil described the bombing as a "terrorist act."
"But it will be premature to speculate who could be behind the explosion and the motives."
The timed device contained 500 grams of explosives, bomb disposal unit official Mohammad Iqbal said.
The blast occurred before staff began arriving at work in the glass panelled building, which houses 120 business offices and is located on the main Sharae Faisal route to the busy Quaid-e-Azam International airport.
A security guard, who was asleep inside the building when the explosion occurred, said he was woken up by "an ear-splitting bang."
"I was hit by a piece of glass and I rushed out where I saw another guard lying on the ground motionless," Mohammad Aslam said.
Police said the powerful blast hurled a body 100m and damaged the first three floors. However, no part of the building collapsed.
Staff working in the offices were sent home by police, who closed the building for the day.
The explosion came a week after a massive suicide bombing which killed 48 people at a Shiite Muslim mosque at Quetta, capital of southwestern Baluchistan province.
Karachi has a history of political, ethnic and sectarian violence which has killed some 4,000 people in the past five years.
It was the scene of a chain of anti-Christian, anti-US and anti-European attacks in 2002, blamed on Islamic militants seeking revenge for the US-led military campaign in neighboring Afghanistan in late 2001.
In two major suicide attacks in May last year, militants killed 11 French naval engineers outside Karachi's Sheraton hotel and a month later 12 Pakistanis died when a bomber blew up his explosive-laden vehicle outside the US consulate.
Late last year seven Christian charity workers were killed in their office and three people were murdered in the honorary Macedonian consulate.