A child has died and rescue workers are battling to save a victim trapped after a massive explosion tore through a house.
A third person is unaccounted for and a fourth, a man, suffered severe burns in the incident, which is thought to have been caused by a gas leak.
The property in Shaw, Oldham, was destroyed and a number of other properties wrecked in the blast.
Superintendent Neil Evans of Greater Manchester Police told reporters at the scene that rescuers could see one person in the rubble.
He said: "One individual we can see, we are trying to remove debris to get that person out."
He added: "This is an ongoing search and rescue effort and we are offering our full support to the fire and other emergency services. Our main and immediate focus right now is to assist in ensuring those injured in the explosion get any medical assistance that they need."
Mr Evans said gas was "one element" the investigation will focus on.
The explosion reduced three terrace houses to rubble.
According to locals, the man seriously injured is named Anthony Williamson and lives at one of the rented properties with his partner, mother-of-six Tanya Williamson.
Hammad Iltaf, whose father is the couple's landlord, said Mr Williamson was at the property with the couple's youngest child.