A young child has been killed and four adults have been injured, two of them seriously, after a suspected gas explosion in Heysham, Lancashire Police said.
A statement by police said: "We remain at scene of a suspected gas explosion on Mallowdale Ave, Heysham which has caused 2 houses to collapse & badly damaged another.
"Sadly, we can now confirm a young child has died & 4 other people have been injured, 2 seriously.
"Our thoughts are with all those affected."
Lancashire Fire said on Twitter that 10 units were called to a row of homes around 2.30am and that firefighters were searching the scene.
"A major incident has been declared after we (were) called to terraced houses on Mallowdale Avenue. It has been reported that there has been an explosion at a property and firefighters are searching the collapsed property," they said.
Lancashire Police tweeted that they had put up a safety cordon and evacuated residents from nearby properties in the town some 25 miles northeast of Blackpool.
"We are asking people to please avoid the entire area while we deal with this ongoing incident," the force added.
The North West Ambulance Service tweeted that it had sent units to the scene, with a priority to "ensure people receive the medical help they need as quickly as possible".
Electricity North West said it had paused power supplies to the area for safety reasons while the blast was being investigated.
Several residents in the area said that up to three houses had collapsed and that emergency services sirens had been heard near the scene for a prolonged time.
Twitter user @murphy30220538 posted a picture of the scene, saying three houses had collapsed after a "terrible explosion" that "sounds disastrous".
People also commented on the loudness of the explosion, including @jstewart668, who said people "heard the bang as far as Lancaster", around nine miles (14km) away.
@ScottLancaster6 said he "heard it in Bowerham", seven miles (11km) from Heysham.
‘I was awoken by a loud bang’: Witnesses describe scene of explosion
Eyewitness by Sadiya Chowdury
The road is littered with roof tiles. It looks like there’s been a hurricane, but the residents of Bowland Street in Lancaster are walking around the aftermath of a gas explosion.
"I was awoken by a loud bang. It sounded like a bomb went off," one resident says to me.
"It sounded like a bomb went off." He guides me through his property to the back garden which is full of debris from the blast. Roof tiles, insulation and chips of wood. "It rained down vertically on us."
Fire and rescue services are still searching the properties at the centre of the blast on Mallowdale Avenue, and a police cordon is in place.
One woman grips the hand of her child. They’re both in bathrobes.
"We’re not so far from the nuclear power station, so we were just assuming," she says. "I could see blue flashing lights, I could hear people screaming.
"Police were telling us turn off your cars and everything like that, and we had to turn off the gas.
"My next door neighbour, she’s really elderly and she was scared to go in. She’d rung three people to get away from the area but no one was answering so she was just going to walk the streets with her dog."
A major incident has been declared after the blast on Mallowdale Avenue, where just the chimney stacks of a row of terraced houses remains.