PESHAWAR, Pakistan (AP) — Authorities say a bomb exploded in a market in a northwestern tribal region in Pakistan that borders Afghanistan, killing at least eighteen people and wounding 51.

Dr. Sabir Hussain at the Parachinar main hospital says 11 critically wounded people brought from the blast at a vegetable market died during treatment. He said there are still several people in serious condition who are being shifted to other hospitals for better care.

Government official Shahid Khan says the explosion took place as the market was crowded with retailers buying fruits and vegetables from a wholesale shop.

Parachinar is the capital of Kurram tribal region which has been the scene of high militant activities in the past years. Army carried out massive operation against militants here but they still have capacity to strike.

No group has claimed responsibility.