A bomber blew himself up at a police station housing the country's terrorism intelligence offices late Monday, killing himself and one officer.
The blast on Pakistan's national day was the first bombing in the capital, Islamabad, since last September, when more than 50 people were killed in a suicide truck bomb attack on the Marriott Hotel.
Islamist militants are blamed for near-daily attacks in the Western-allied but increasingly unstable country, though little information on Monday's bomber was yet available.
The man detonated explosives at the gate of the police station in the center of the capital, Interior Ministry secretary Kamal Shah said. He said an officer who was apparently challenging the bomber died in the blast.
The police station houses the offices of the Special Branch, which is responsible for intelligence gathering about terrorism, sectarianism and political activities in Pakistan.
"We were on high alert, but there is no way to detect a person who is determined to blow himself up," Interior Ministry chief Rehman Malik said.
Pakistan is under intense Western pressure to crack down on the militants, many of which are believed linked to al-Qaida. They are also blamed for attacks on U.S. troops in neighboring Pakistan. The terrorists are believed to have established safe havens in tribal regions close to the Afghan border.
