At least 12 people including two children were killed and dozens of others were wounded in an apparent gas cylinder explosion at a Turkish restaurant in the Qatari capital of Doha.

The blast happened on Thursday at about lunchtime, and caused extensive damage to the Istanbul Restuarant, which is next to a petrol station near the Landmark Mall shopping complex.

Major General Saad bin Jassim al-Khalifi, Qatar's head of public security, said non-Qatari Arabs, Asians and one Qatari
were among the dead and wounded.

"It was a very big blast," he said. "It blew away cars and shrapnel was scattered 50m to 100m away."

Preliminary investigations suggested a gas tank exploded, setting off a fire and causing part of the building to collapse, he told a news conference.

Officials were treating the explosion as an accident, though it is unclear what ignited the tank.

Another 32 were injured, three of them critically, the official Qatari News Agency reported.

Chunks of masonry, metal debris and shattered glass lay outside the restaurant in a northwestern district of the city. Cars nearby were apparently crumpled by the explosion.

At least three of those reported injured are from the Philippines, and two of them are in the intensive care unit of Hamad Hospital, a representative of the Philippine Embassy in Doha told Al Jazeera.

The same source also told Al Jazeera that two migrant workers from the Philippines are confirmed dead. They reportedly worked as staff of a store next to the restaurant.

Footage showed paramedics carrying a covered body past rubble strewn some 50m from the building, whose roof had caved in.

Alexandra Permuy, 25, a graduate student from Miami who lives nearby, was startled awake by the explosion.

"At first I thought it was just thunder...but when I looked out the window there's not a cloud in the sky,'' Permuy told the Associated Press news agency.

In another incident on Thursday, the Reuters news agency reported that dozens of people had been injured in a leak at a chemical facility in an industrial area just outside Doha.

Nineteen people were killed in a May 2012 blaze at a major Doha mall, including 13 children and four supervisors at a nursery located within the shopping centre.

Al Jazeera