Officials said a vehicle loaded with about 90 pounds of explosives was detonated by remote control in Jamrud, near Peshawar, which borders the tribal region along Pakistan's border with Afghanistan, The New York Times reported.
The blast occurred near the offices of a senior government official, but its force tore through a women's waiting area of a bus stop, Jahangir Azim, a senior official in the Khyber agency, said.
Four Afghan woman and three children were among the dead, Azim said.
No one claimed responsibility immediately after the explosion, which damaged several nearby businesses and vehicles.
Officials said at least 44 people were wounded.
"At the moment we are not in position to allege someone for the blast or to tell exactly what was the motive behind the attack by the perpetrators," Asmatullah Wazir, a local official, told the Times.
The Khyber agency is a haven to several Islamist militant groups.