A child has died and four people have been injured after a major explosion destroyed terraced houses.
Two people have been seriously hurt after a suspected gas explosion hit up to three terraced houses in the middle of the night.
Police raced to the scene at 2.40am after reports "a number" of houses had collapsed in Heysham, Lancashire.
Firefighters and paramedics also scrambled to help after residents were woken by the sound of a blast
In a statement, the force said: "We are currently at the scene of a suspected gas explosion on Mallowdale Avenue, Heysham.
"We were called at 2.40am... to reports that a number of houses on the road had collapsed.
"Our officers are at the scene along with our colleagues from Lancashire Fire and Rescue and North West Ambulance Service.
"A safety cordon has been put in place and nearby residents have been evacuated."
Lancashire Fire said on Twitter that 10 units were called to the terraced row and that firefighters were searching a collapsed property.
"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," Lancashire Fire said.
No information on any casualties was immediate available, but several residents of the area tweeted that up to three houses had collapsed, and that emergency services sirens had been heard near the scene for a prolonged time.
Dan Knowles, who lives four streets away from the explosion, said he had thought there had been an earthquake.
"My wife and I thought there was an earthquake which woke us, the whole house shook," he told the PA news agency.
"We immediately checked on our kids and got back in bed. We then heard sirens and my wife checked Facebook, when we found out that there'd been a gas explosion. We stayed indoors and switched everything off at the source and then sat up all night worrying."
Lancashire Police said a safety cordon had been put in place and nearby residents in the town, about 25 miles north-east of Blackpool, had been evacuated.
"We are asking people to please avoid the entire area while we deal with this ongoing incident," the force said.
Local MP David Morris, who represents Morecambe and Lunesdale, wrote on Twitter: "My thoughts and prayers are with all of the families on Mallowdale Avenue following the incident this morning. Thank you to all of the emergency services who are currently on the scene."
The North West Ambulance Service tweeted that it had also sent units to the scene, with a priority to "ensure people receive the medical help they need as quickly as possible".
Electricity North West wrote on social media that it had paused electricity supplies to the area for safety reasons while the blast was being investigated.
