Bus Bomb Kills 7 in NW Pakistan

Pakistani police officers look at a damaged vehicle following blast in Peshawar, Pakistan, Oct. 2, 2014.

At least seven people were killed when a bomb exploded on a passenger bus in northwest Pakistan.

Officials say four people were also injured in Thursday's attack, which took place on the outskirts of Peshawar, the region's main city.

Police say the bomb was planted beneath a passenger seat.

No one has claimed responsibility for the attack, which comes as Pakistan's army continues a months-long offensive targeting Taliban and foreign militants in tribal areas.

Peshawar is located on the border with Pakistan's semiautonomous tribal region.

The Pakistani Taliban has carried out many bombings in Peshawar, targeting security forces and civilians.