A neighbour has described hearing a woman screaming at firefighters to "save my house" as they tackled a blaze which killed two people and left four children and a man injured.
A man and a woman died at the scene of the house fire in Withington, Manchester, where emergency services were called at about 2.20am on Friday.
Greater Manchester Police said three girls and a boy, aged between 10 and 17, were taken to hospital, where they are being treated for their injuries.
Another man was also taken to hospital and remains in a serious condition.
Neighbours said a "quiet and polite" Asian family lived at the address, a detached house on a tree-lined road of semis, formerly family homes, many converted into student houses, around a mile from Manchester University.
Student Emily Puckering, 22, from Hull, said she was woken at about 2.30am by shouting and screaming as fire engulfed the house across the road.
Miss Puckering said: "I could just see the smoke at first. When I woke up I realised how severe it was. I could see the flames coming out of the windows.
"My initial reaction was to phone the fire brigade but I could see the fire brigade had just turned up.
"From my window I could just see flames and smoke. I couldn't see people in the house, I could just hear them.
"I could hear a woman, she was shouting and screaming. I'm assuming it was her house because I could hear her shouting to the fire brigade, 'Please save my house'.
"Finding out they passed away this morning is heartbreaking, it's such a tragedy, especially seeing as it's possibly a crime scene now.
"The fire service was absolutely amazing.
"There was three fire engines, two police cars, an ambulance, another van, I think, just from the council. A big response.
"They put the fire out quite quickly. The fire itself was massive, it was huge.
"It's heartbreaking, it's absolutely tragic. I just feel a bit shocked. I just feel absolutely awful for them, for the family, for the children, for them.
"I can't imagine anything worse at all.
"And to see it as a crime scene as well is even worse, down the street where I live. It's absolutely heartbreaking."
Police launched a joint investigation with Greater Manchester Fire and Rescue Service (GMFRS) to establish the cause of the blaze.
The road was blocked off with police tape and police and fire service vehicles stood outside the house, with its smoke-blackened upstairs windows wide open.
Fire and crime scene investigators put on white body suits as they carried on their work, taking photos and carrying equipment into the property.
Detective Inspector Tony Lea said: "My thoughts are with the family of the man and woman after such a tragic incident and we have specially-trained officers supporting the family at this time.
"We are continuing to work closely with GMFRS to establish exactly how this fire started and I urge anyone who may have witnessed the fire, or anyone in the area in the hours before the fire.
"If you have any information at all contact police as soon as possible so we can piece together what happened."
The force spokesman said next of kin had been informed but the bodies had yet to be formally identified and post-mortems had not yet taken place.
Anyone with information should contact police on 101 quoting incident number 140 10/02/17 or the independent charity Crimestoppers, anonymously, on 0800 555 111.
The family are believed to be originally from Gaza in the Palestinian territories, according to neighbours.
Two security cameras were positioned at the front door and another on the corner of the house.
Police said they believe there is no reason anyone would want to harm the family.
Speaking at the scene, Chief Superintendent Was Chaudhry, from Greater Manchester Police, said the two victims were found dead at the house and described it as a "tragic incident".
He said the cause has not yet been determined as an investigation is still in its early stages. He made a public appeal for information and said officers had not ruled out foul play.
Mr Chaudhry said: "We follow a number of routes, whether that's a crime investigation, whether that's something that has happened in terms of with the electrics, the gas, utilities etc.
"We have got to keep an open mind in terms of this whole investigation. There's a number of hypotheses that we are following and it would be remiss of us at this stage just to narrow that investigation down without appealing for witnesses.
"I would also like to appeal to the public, to local residents, that if they did see anything happening, shortly before 2.30am and during the course of the police and fire service response, then please contact us. That information could be the missing part of our overall investigation."
He said the CCTV at the house will form part of the police inquiry.
He also paid tribute to the neighbours who helped rescue the family: "Without their help I'm sure other people would have suffered more serious injuries and possibly even fatalities as well."