A bomb exploded on a passenger bus in the outskirts of Peshawar in Pakistan’s northwest on Thursday, killing at least seven people. Though no group immediately took responsibility for the attack, police officials reportedly said the act seemed to be linked to terrorism.

The bomb was reportedly placed under a seat on the bus, while local reports said that the officials found 11 pounds of explosives in connection with the explosion, Dawn, a local newspaper reported. The explosion comes as Pakistan’s military has waged a war against militant groups in the northern region of Waziristan, which has displaced more than 800,000 people. More than 910 militants have been killed so far in these attacks, which started in June, and the military claims to have captured over 100 more.

"Those who orchestrated the attack will not go unpunished," Shafqat Malik, a senior police officer, said according to Associated Press.

Police officials and rescue workers were trying to control the fire caused by the explosion, while the injured were taken to a nearby hospital, Dawn reported. At least 11 people were injured in the attack, while six were injured, according to Agence France-Presse.