At least four people were killed in separate incidents of wall and roof collapse in Karachi on Friday as gusty winds battered the city, turning the weather dusty.

The Met Office said in a statement that strong winds were blowing in the city from the west at 25-30 knots (1kn equals 1.852 kilometres per hour) as the result of a "steep pressure gradient".

Sardar Sarfaraz, chief meteorologist at the Met department, further explained in a video clip that the pressure gradient was high in western Balochistan and Iran due to the presence of a westerly low-pressure weather system in the eastern parts of Balochistan adjoining south Punjab and upper Sindh.

This, he said, had triggered gusty winds in Karachi.

He added that the speed of winds was increasing to 35kn in some areas.

Sarfaraz said the windy and dusty weather in the city was likely to continue till midnight.

He said strong winds could cause trees to fall and damage "loose structures" such as tents.

Separately, the Met Office issued a weather advisory, which said Sindh, including Karachi, was likely to experience a "mild cold wave" between January 22 and January 27.

During this period, the advisory said, night temperatures in most cities of Sindh were expected to drop to four degrees Celsius to six degrees Celsius and in Karachi to eight degrees Celsius to nine degrees Celsius.

It added that weather was likely to remain cloudy and there were chances of light rain in Sukkur, Ghotki, Khairpur, Larkana, Jacobabad, Kashmore, Shikarpur and Qambar-Shahdadkot.

The advisory said dry weather, cold nights and foggy mornings would be experienced in plain areas elsewhere in the province.

One child among four dead as roofs, walls collapse

Meanwhile, four deaths were reported as strong winds caused walls and roofs to collapse in different areas of the city.

Taimuria Station House Officer (SHO) Abdul Rasheed said a man was killed in a wall collapse caused by gusty winds near Five Star Chowrangi in North Nazimabad's block L.

He said the incident took place around 1:15pm when the wall of a library collapsed.

The SHO said the deceased man, 60-year-old Ratan Bagh, used to sell flowers in the area.

"He was sitting against the wall when it collapsed as strong winds blew," he said, adding that the deceased person's brother, who was at a distance from him at the time of the incident, remained safe.

His body was shifted to Abbasi Shaheed Hospital for the completion of medico-legal formalities.

Later, Surjani Town SHO Haji Sanaullah confirmed another death caused by a wall collapse.

He said a seven-year-old boy, Abdul Rehman, died after a wall collapsed on him due to strong winds in Surjani Town's Rahim Goth, near Kaneez Fatima Society.

The boy's body was shifted to Abbasi Shaheed Hospital, SHO Sanaullah said, adding that his relatives did not allow doctors to complete medico-legal formalities and took the body away.

Meanwhile, another death caused by a wall collapse was reported from Gushan-i-Maymar.

Gulshan-i-Maymar SHO Riaz Ahmed Bhutto said Rehmatullah, 50, died when a wall collapsed on him due to strong winds.

He said Rehmatullah was a labourer and was working in a slum when the incident took place.

His body was shifted to Abbasi Shaheed Hospital.

Another labourer, 58-year-old Faqir Muhammad, died while working in Sher Shah as a the wall of a house collapsed on him, SHO Mehmood said.

He added that Muhammad had sustained severe injuries and died on the way to Dr Ruth Pfau Civil Hospital, Karachi.

The SHO said Muhammad's relative did not let doctors complete medico-legal formalities and took his body away.

According to a statement issued by the Mochko police, three persons sustained injuries when the roof of their house collapsed in Mowach Goth.

The injured, Abdul Ghafoor, 55, his wife, 50-year-old Hameeda and Hurma Rauf, 18, were shifted to Dr Ruth Pfau Civil Hospital Karachi, the statement said.

Moreover, another man was injured in a wall collapse incident in Indus Town off the Superhighway, SHO Bhutto said.