Three people were killed and more than 20 injured on Saturday when a suicide bomber rammed a van packed with explosives into a police station in northwest Pakistan.
"The attacker detonated his pick-up van at the gate of the main police station in Karak town" of North West Frontier Province, local police chief Sajid Mohmand told AFP.
"Two policemen and one civilian were killed."
At least 26 people were wounded, including 21 policemen, he added.
Local hospital doctor Nazrul Islam said some of the wounded were in a serious condition.
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The bombing badly damaged the building while two police vehicles were also damaged, police officer Imtiaz Ahmed said.
Karak is located 150 kilometres southeast of Peshawar, capital of North West Frontier Province, which has been plagued by militant violence including bomb attacks blamed on Taliban and al-Qaeda-linked militants.
The bombing took place as Muslims across Pakistan staged rallies to celebrate the anniversary of the birthday of the Prophet Mohammad.
It follows a clash in the nearby garrison city of Kohat on Friday in which Pakistan security forces killed 17 militants, officials said.
Pakistan's military has launched a number of offensives against Islamist militants in the tribal belt where the United States says al-Qaeda has carved out its headquarters in the most dangerous terrain on Earth.
Pakistan is under increasing US pressure to do more to act against militants who stage cross border attacks in Afghanistan against NATO and US forces fighting an eight-year war against the Taliban.
More than 3,000 people have been killed in suicide and bomb attacks across Pakistan since July 2007 in a deadly campaign blamed on Islamist militants opposed to the government's alliance with the United States.
