Islamabad, Pakistan (CNN) -- Six people were killed and 18 wounded in a blast in Pakistan's tribal region Friday morning, a government official told CNN.
The blast occurred in the Khyber district -- the main supply route for NATO and U.S. troops in Afghanistan.
It went off in the Tirah Valley at a market where a weekly used-car auction was being held, said local official Rehan Gul Khattak.
The area has been the site of ongoing clashes between militant group Lashkar-e-Islam and its rival, the Taliban.
Journalist Nasir Habib contributed to this report