Islamabad, Sep 27 (IANS): At least 17 people were killed and over 34 injured Friday afternoon when a blast hit a bus carrying government employees in Pakistan's northwest city of Peshawar, an official said.

Sahibzada Andes, commissioner of Peshawar, said the blast took place at 12.30 p.m. when a bomb exploded inside the bus which was on its way back from Peshawar to Charsadda, a neighbouring town, 20 km north of Peshawar, Xinhua reported.

Bomb disposal squad officers said the bomb was placed inside a carton which was kept under the back seats of the bus and it was detonated through a time device.

An estimated six to eight kg of explosives were used in the bomb, they said.

The bus was severely damaged following the blast.

There were at least 50 people in the bus when the blast occurred, media reports said.

The people in the bus were employees working for the civil secretariat in Peshawar.

Some of the injured were brought to Peshawar's Lady Reading Hospital while others were shifted to the district headquarters hospital in Charsadda.

Hospital sources said some of the injured were in critical condition and the death toll may rise further.

No group has claimed responsibility for the attack yet.