Islamabad, Oct 21 (IANS): Four people were killed in an explosion targeting law enforcement officials in Pakistan's Khyber Pakhtunkhwa province, a senior police official said.

Wednesday night's victims comprised two policemen and two Frontier Corps (FC) personnel, who were investigating another blast that also took place in the same area in Bajaur district, District Police Officer Abdul Samad Khan told Xinhua news agency.

"In the afternoon blast, some elders from the area were injured when their vehicle was attacked near the Pakistan-Afghanistan border. When the police and FC reached the site for investigation, the second and major blast happened, leaving the four killed right at the spot."

He said that both attacks were launched by improvised explosive devices fixed and hidden in the grass near the road.

"A joint investigation and a search operation by police and FC are underway in the area, and we will be able to trace and nab the fleeing militants soon," he added.

No group or individual has claimed responsibility for the attack yet.

Once a hotbed of militancy, the tribal districts of the country including Bajaur started to see peace, following extensive operations by the Pakistani military to flush out militants.