Nine people have been injured by a gas explosion which destroyed a row of homes and left firefighters battling to establish if anyone was trapped in the rubble.
At least three homes were damaged in the blast which happened in Salford, Greater Manchester just before 7.15am, police said.
A Greater Manchester Fire and Rescue Service spokesman said: "There are people trapped and we're trying to rescue them at the moment."
A number of roads, including Silver Street, Merlin Road, Morrillion Road and Cutnook Lane were closed off while police and other emergency services worked at the scene, Greater Manchester Police said.
A North West Ambulance spokesman said a woman in her 70s was taken to Wythenshawe Hospital with 30% burns.
There were also five walking wounded - two adults and three children.
Silver Street resident William Billinge was woken up by a "very loud bang" and he said the explosion shook his house.
When he went outside to find out what had happened, he described seeing four houses in Merlin Road destroyed.
Mr Billinge, 65, said: "There's nothing left of them.
"There is debris everywhere, all over the place.
"Four houses completely flattened."
He said the area was "chock-a-block" with emergency services.
Barbara Holgate had just returned home from working a night shift at Tesco when she heard the explosion.
"They have evacuated a lot of people," she said. "They were knocking on doors telling people to get out.
"Apparently they have opened a school in Fiddlers Lane for them to go to.
"But it's a close-knit area so people have been going to relatives and friends. I've invited somebody in for coffee.
"They told most people to go inside. There's a big smell of gas."
Carolyn Patten, 64, a retired office worker, said she was woken up by the blast.
"There was a huge booming noise at around 7am this morning," she said.
"The road is just adjacent to the M62, so I just thought it was a crash on the motorway.
"Then pretty quickly we heard all the sirens and realised that something was going on down the other end of the road.
"We've been told a number of houses have been flattened and around seven people have been taken to hospital."
Mrs Patten said the houses affected by the blast were built in the 1960s and were ex-council stock.
Fiddlers Lane Community Primary School, in Fiddlers Lane, was closed to pupils due to the explosion but was providing shelter for evacuated residents.
Headteacher Julie Carson said: "We've opened up our hall and we are providing snacks and drinks.
"We are working with the council."
At around 10am, Carol Ward, of Morillon Road, said the police had asked them to leave their homes for their own safety.
Mrs Ward said: "They have cordoned off outside our houses and we have been asked to lock up our houses and leave.
"I am going to my daughter's if the roads aren't all blocked off."