**A suicide bomber has blown himself up near the entrance to the headquarters of the Pakistani navy in centre of the capital, Islamabad, police have said.**Officials said they believed four people had been hurt, one critically.
Witnesses said the attacker detonated his explosives when challenged at the gate of the navy complex in the E8 sector, near the busy Margalla road.
The Pakistani security forces have been targeted in a series of attacks in recent months by Islamist militants.