Five police officials and two civilians were killed by the second blast and 16 police were among the wounded, Khan said.
Amanullah Khan, a wounded police official, said he and his colleagues were attending to four civilians injured by the first explosion when the bomber attacked.
"When I stood up, there was blood everywhere," said Khan. "My colleagues were crying with pain."
During a raid elsewhere in northwest Pakistan on Sunday, the army discovered a van packed with 880 pounds (400 kilograms) of explosives. The van was intended to be used in a suicide bombing, the army said.
Six suspected militants were arrested in the raid on a house in the Khyber tribal region, the army media center said. The army also found suicide jackets, rockets, assault rifles and improvised bombs in the house.
The army has been in Khyber trying to secure the main supply route for U.S. and NATO forces in Afghanistan. Information from militants arrested during the operation led to Sunday's raid, said the army.
