Six people – including a police officer and three children – were transported to hospital following a house fire in Markham Tuesday afternoon.

Emergency crews were called to a home on Douglas Haig Drive, in the McCowan Road and Steeles Avenue area, just before 5 p.m.

Preliminary reports indicated that a house had exploded.

One witness at the scene described seeing a “big cloud of black smoke” in the area.

“When I got here, you could see fire jumping up in the air,” John Boyles told CP24 at the scene.

“People were running out,” witness Lori Judge described.

“They had their pajamas on, shorts on… just the clothes on their back. Some people didn’t have jackets or sweaters or anything.”

Residents were evacuated from surrounding homes as a precaution while Markham firefighters worked to suppress the flames.

According to police, six people – two men, a woman, and three children – were transported to hospital.

One of the men – a police officer – was transported to hospital as a precaution suffering from smoke inhalation, police said.

The other man suffered serious injuries, York Regional Police Const. Laura Nicolle said at the scene. She described the injuries to the woman and the children as minor.

Details on the gender and ages of the children were not immediately provided.

The police officer, woman and children have since been released from hospital.

The cause of the fire was not immediately clear.

“It’s too early in the investigation to say what the cause is,” Nicolle said.

The office of the Ontario Fire Marshal is investigating.

Crews remain at the scene.