A bomb explosion hit the heart of the Pakistani capital on Saturday morning and police said it was caused by a suspected suicide bomber whose vest may have detonated prematurely. The suspected bomber was in critical condition after the blast at a popular complex of shops in Islamabad but no one else was wounded, a senior policeman at the scene told Reuters. The blast came after a week when Pakistani military jets pounded suspected militant hideouts. Ground troops also moved into a small portion of North Waziristan, an area on the Afghan border considered the main stronghold of Taliban forces. Islamabad has been relatively peaceful in recent years, but in the past few months it was hit by an attack on the district court and a bombing at a vegetable market that killed 22 and wounded scores of others.