Islamabad, Aug 19 (IANS): Two policemen were killed and another was injured in an exchange of fire in Pakistan's northwestern Khyber Pakhtunkhwa province, police officials said on Sunday.

The incident happened in the Bargai area of the Lakki Marwat district of the province when unknown terrorists attacked a police vehicle, killing two policemen while injuring another senior police officer, Xinhua news agency reported, quoting police sources.

The policemen were attacked during a routine patrol in the area, said police, adding that two terrorists were also injured in the retaliatory fire.

Following the incident, an additional contingent of police along with rescue teams reached the scene and shifted the injured to a nearby hospital.

Police have started an investigation and launched a search operation in the surrounding areas to arrest the accomplices of the terrorists involved in the attack. No group has claimed the attack yet.