ISLAMABAD, Sept. 3 (Xinhua) -- At least six people were killed when a passenger vehicle came under attack in Pakistan's northwest Khyber Pakhtunkhwa province on Wednesday, the police said.

The incident occurred in a rural area of Kurram District, where unknown assailants opened fire on the vehicle, Regional Police Officer of Kohat region Abbas Majeed Marwat said in a statement.

He said police and security forces immediately launched a search operation in the area following the attack.

So far, 12 suspects have been taken into custody, and a cache of weapons has been recovered during the ongoing operation, Marwat added.

Heavy contingents of police and security personnel are conducting house-to-house searches in the area to trace the attackers. No group has claimed the attack yet. ■