Six persons of a family, including three children, died of suffocation after gas from a heater filled the room they were sleeping in at a relative's house in the Gulshan Colony area of Khyber Pakhtunkhwa's (KP's) Hangu city, police said on Tuesday.

According to Hangu police spokesperson Zahir Hussain, the family was visiting their relatives in Gulshan Colony, in the remits of City police station, and stayed at their house overnight.

They had left the heater switched on before going to sleep because of the cold weather and died of suffocation, he said.

Special Assistant to the KP Chief Minister on Information Barrister Mohammad Ali Saif expressed grief over the incident.

In a statement, he said he was deeply saddened by the unexpected deaths of six persons of a family and appealed to citizens to exercise caution while using gas heaters in winters.

Earlier this month, at least six more incidents of similar nature were reported in KP.

Dawn reported on December 18 that two siblings were suffocated and nine others had fallen unconscious in different areas of Mansehra city and its suburbs over the past two days as they went to sleep without switching off gas heaters.

The two siblings — Ayesha Bibi, a college student, and her brother, Mohammad Usman, who studied in the ninth grade — died in the Dub area of the city.

They had not turned off the gas heater before going to sleep and died of suffocation as poisonous fumes filled their room, Rescue 1122 District Emergency Officer Hafeezur Rehman told reporters.

He further stated that six members of a family fell unconscious in a similar incident in Township areas and were shifted to King Abdullah Teaching Hospital.

Separately, he added, three women had fallen unconscious in Batdarian area in another incident of such nature.

On the night of December 22, four persons were suffocated to death and 10 others had fallen unconscious due to gas leaks from heaters in separate incidents in KP.

According to Rescue 1122, two friends identified as Israr Khan and Mohammad Usman were suffocated to death as they went to sleep without turning off the gas heater in the Khwazakhela tehsil of Swat.

In a similar development, eight persons had fallen unconscious after gas leaking from a burning heater accumulated in the hotel room they were sleeping in at Fizagat in Mingora.

Meanwhile, a woman and her daughter-in-law had died of suffocation and two others from the family had fallen unconscious in Mohallah Usmania in Mansehra.