Six members of a family were killed in a "mortar shell" blast inside their residence in Khyber Pakhtunkhwa's Bannu district on Tuesday evening.

According to District Police Officer Bannu Yasir Afridi, the explosion took place inside a room of the house situated within the limits of Haved police station.

It occurred when a 60-millimetre mortar shell exploded inside the house, according to KP police spokesperson Waqar Khan.

As a result, a man — who was a teacher — his wife and their four children were killed.

The spokesperson said it had been confirmed that the blast was caused by some sort of an artillery shell. Police cannot say at this point exactly what type of shell it was and whether it was lying inside the house or came from the outside, the official told DawnNewsTV.

However, he added that police have collected all evidence which will be examined in the laboratory to determine the nature of the explosion.

DPO Afridi had earlier said a bomb disposal squad was at the site of the incident and that an investigation into the incident was underway.