A seven-year-old boy has died after a "devastating explosion" in a residential street in Newcastle.
Three adults and a child were taken to hospital after the incident on Wednesday.
Emergency services were called to Violet Close, in the Benwell and Elswick area of the city, shortly before 1am.
A spokesman for North East Ambulance Service said that four people were treated at the scene and taken to hospital.
Drone pictures showed at least one house appeared to have been completely destroyed, with roofs collapsed and firefighters working among the rubble. Piles of debris could be seen on the street outside.
A family friend of some of the victims said that there had been a "devastating explosion".
Andy Riches, a safety steward at Newcastle United, has set up an online fundraiser in aid of the occupants of one of the homes affected.
He is friends with the grandfather of a couple with two children who live in one of the flats, and said: "They have lost everything."
Residents are being advised to keep windows and doors closed, while motorists are asked to avoid the area with road closures in place.
A spokesman for North East Ambulance Service said: "We were called to an incident in the Elswick area of Newcastle at 12.45am today.
"We dispatched four paramedic crews, four crews from our hazardous area response team (Hart), a doctor, a specialist paramedic, a clinical team leader, a duty officer and a tactical adviser to the scene.
"We treated and conveyed four patients - three adults and one child - to hospital for further treatment."
A Northumbria Police spokesman said: "Shortly before 12.45am today (Wednesday), police were contacted by Tyne and Wear Fire and Rescue Service, who are dealing with a fire at an address in the Violet Close area of Newcastle.
"Emergency services remain in attendance at the scene.
"Road closures are in place on Buddle Road and the surrounding area, and motorists and residents are advised to avoid the area and to keep doors and windows closed if they see and smell smoke."
Tyne and Wear Fire and Rescue Service tweeted in the early hours of the morning: "We currently have several firefighting appliances in attendance at a large-scale incident in Violet Close, Newcastle.
"Please avoid the area and keep doors and windows closed until further notice."
Firefighters continued to work at the scene using a jet to damp down the house, which was still smouldering.
A fire service van marked "search dogs" was parked nearby, as were specialist gas engineers, while vehicle recovery workers were seen taking away several damaged cars on low-loaders.