Article published on the 2008-10-16 Latest update 2008-10-16 13:52 TU
Three security personnel and one policeman were killed and most of the 30 injured were security forces and police. Mingora city police chief Dilawar Khan Bangash told Agence France Presse that two civilian bystanders were also hurt.
"It was a huge blast. Three security force personnel and one policeman were killed. The police station was destroyed," he said.
Under pressure from the United States, the government is cracking down on militants with links to Al-Qaeda and the Taliban in the region.
Most of the Swat Valley is now under military control the army said earlier this week.
Security forces in the mountainous Swat, which is a former tourist resort, have been fighting militants who tried to enforce Islamic Sharia law last year.
The government attempted to persuade independent ethnic tribesmen to assist in its military operations, but militants have fought back, killing dozens of security forces and tribal elders they claim to be on the government's side.
The attack came a month after 60 people were killed in a suicide bombing at the Marriott hotel in the capital Islamabad.