Members of the York Regional Police Service’s homicide unit have taken over an investigation into a fatal house explosion in Markham that claimed the lives of two children.

On May 17 shortly before 10 a.m., emergency crews were called to a residence on Bur Oak Avenue for a reported fire. Crews arrived on scene to find that there had been an explosion at the home, which subsequently caught fire.

A 41-year-old mother and two of her sons, ages 6 and 14, were transported from the scene to hospital in critical condition.

A 12-year-old boy, who was initially unaccounted for following the fire, was later found dead inside the home two days later.

More than two months after the fire, the six-year boy, who was receiving treatment in hospital, also died from his injuries.

Family members have identified the two brothers as 12-year-old as Aran Hamid and six-year-old as Zheer Hamid.

"The 14-year-old and the 41-year-old mother spent a long period of time in hospital. They have since been released from hospital," Sgt. Andy Pattenden told CTV News Toronto on Tuesday.

The children’s father was away at the time of the explosion, police said.

"There was a reason why he was away from the house during the explosion and that is something that has obviously been investigated right since the incident had taken place. But it is still part of the ongoing investigation,” Pattenden said.

The Office of the Fire Marshal (OFM) conducted an investigation into the explosion and the findings were recently shared with York Regional Police.

"It has taken quite a long time for the fire marshal's office to work through their lengthy investigation. And with their report that has come back, the fire has been deemed suspicious and that is why our homicide unit has taken over," Pattenden said.

He noted that the cause of the explosion has been determined but police will not be releasing that detail.

"What they (homicide detectives) are appealing for now is anyone that might have had any information on the family, on why this explosion may have occurred at the home," Pattenden said.

"They have spoken with everybody who survived this terrible explosion but they are really looking for anyone else who might have information to come forward."

He said police have not yet identified any suspects.