Tributes have been left at the scene of an explosion in the Shaw area of Oldham that killed a two-year-old and left a 27-year-old man in a critical condition.
Greater Manchester Police said they were treating the death of Jamie Heaton as suspicious, saying a homicide investigation was underway.
Anthony Partington, 27, who is no relation to Jamie, was left with life-threatening burns after three terraced homes were reduced to rubble.
Sources confirmed a domestic argument involving the injured man took place in the hours before the blast, with his partner leaving their house with her five children.
A police handout of Jamie Heaton, who died in the explosion
Steve Heywood, Assistant Chief Constable of Greater Manchester Police, told a press conference in Shaw: "We have had some information to suggest it may not be accidental so we are treating it as a suspicious death and therefore a homicide investigation is undertaken."
Police said they were aware of rumours about a domestic incident and appealed for information, adding they had "significant questions" for Partington, who has officers waiting at his bedside for him to regain consciousness.
Two-year-old Jamie Heaton died after what was believed to be a gas blast tore through three houses in Buckley Street reducing them to rubble.
Jamie's mother is said to have gone out to the yard to hang out the washing when the explosion occurred, while her son was watching TV, according to police. The Telegraph reported his mother crawled through the rubble of the collapsed house to find her son.
"The victim Jamie was in the house, we believe the front room, watching TV and his mother had just slipped out into the back yard, hanging out washing," Steve Heywood, Assistant Chief Constable of Greater Manchester Police, said.
"What that mother must be going through must be unbelievable, so our hearts go out to her."
Superintendent Neil Evans said on Tuesday: "We are also aware of some rumours within the local community about a potential domestic disturbance in the area last night.
"What I can categorically say is that if that is the case, the police were not called.
Tributes were left at the scene of the gas explosion
"However, if anyone has any information about this, particularly if they think it might be relevant to what happened today, I would urge them to get in touch."
The officer said of the dead child's family: "His loved ones are absolutely distraught and we will provide them with whatever support we can at what is clearly a very difficult and upsetting time."
One message on a bunch of flowers read: "Our thoughts are with you and your family little angel, taken so early."
The scene was described as looking like a war zone by residents
Adam Pollard, 21, was at his mother's house just 500 yards away when he heard the explosion.
"It was the biggest bang I have ever heard, all the windows shook," he said.
"I got to the street and the three houses that had been there were just rubble. I was worried if someone was trapped."