The bomber was killed in the attack.
The attack came a day after a suicide bomber rammed a car packed with explosives into a police checkpost in the volatile Swat valley in northwest Pakistan on Sunday, killing six people.
Earlier on Sunday the commander of the military operations in Swat had said that his forces had retaken all the towns in the valley seized by the militants, killing 290 of them and capturing 140.
There has been a spate of suicide attacks blamed on Islamist militants since a military assault on the Red Mosque, a militant stronghold, in Islamabad in July.
More than 800 people have been killed in ensuing violence across the country since then, about half of them in suicide attacks.
Pakistan, a key ally of the United States in its so-called "war on terror", has witnessed scores of attacks that have claimed hundreds of lives in the past several years.
Fighters this summer seized tracts of the area, a former tourist destination 160km from the capital, Islamabad.