The bomber rammed his motorcycle into the roadside checkpoint in the Jamrud area of Pakistan's volatile Federally Administered Tribal Areas, local government official Munir Khan told Reuters.
"He was riding an explosives-laden motorcycle and hit the checkpoint and the vehicle of the line officer," Mr Khan said.
Among the dead were at least five police officers including the line officer whose vehicle was targeted by the bomber, and a journalist, officials said.
The attack took place in an area where security forces have stepped up their fight against Pakistani Taliban and other militant groups along the border with Afghanistan, following the massacre of more than 150 people, mostly children, at an army-run school in December 2014.
Attacks have fallen since the government crackdown and the Taliban squeezed into small pockets of territory, but militant groups remain able to launch hit-and-run and suicide attacks on security forces.
A spokesperson for the Hayatabad Medical Complex in Peshawar, to where the wounded were evacuated, said earlier that the hospital had received six bodies, including that of a child.
No one has claimed responsibility for the blast.
Last month, a suicide bomber attacked a government office in northwestern Pakistan, killing at least 23 people.