There were no previous complaints about dangerous dogs at a house where a 14-year-old girl is thought to have been killed by a pack of "aggressive and out-of-control" dogs, police said.
Jade Lomas-Anderson's body was discovered with wounds consistent with a dog attack shortly after 2pm on Tuesday, following reports she was unconscious.
Superintendent Mark Kenny of Greater Manchester Police said: "The most likely scenario is that Jade was attacked by four dogs, that is still part and parcel of the investigation. That clearly is the most likely scenario of what's happened but we're looking obviously at all options."
He said the attack would have happened between 1pm and 2pm.
Jade was described as 'shy' by friends (Pic: Facebook tribute page)
A post-mortem examination is due to take place later.
The teenager was visiting the house in Chaucer Grove, Atherton, near Wigan, and was alone with the dogs, believed to include two bull mastiffs and two Staffordshire bull terriers.
Four animals were shot dead by police marksmen and a fifth was contained.
Supt Kenny said: "We have had no contact or reports, Greater Manchester Police, regarding reports for example of dangerous dogs at this location. We've certainly not had any incidents here.
Two dogs were believed to be Staffordshire bull terriers (file picture)
"This is the first incident of this nature we have attended at this location."
Officers have spoken to the owner of the dogs, the owner's family and neighbours since Jade was found.
Friends have paid tribute to the "quiet" and "timid" teenager, who is thought to have returned to the property from the shops with a meat pie when she was attacked.
Flowers were laid at the backyard where Jade was attacked. A sign on the gate read: "Beware of the Dog."
Locals said Jade was there to see a friend, Kimberley Concannon, 16, who lives there with her twin Catrina and mother Beverley Concannon.
One 15-year-old said of Jade: "She goes to my school in the year below.
"She's shy, quite timid, if you didn't know her you wouldn't recognise her around and about. It's horrible what's happened.
"She picks her little sister up Sienna from school, every day and walks past my house.
"She had a pie in her hand and has gone to bite it, she moved the pie and the dog's gone for her throat and then they have all gone for her."
Another friend said the dogs at the house were large and aggressive animals.
Friends are said to be 'deeply shocked' (Pic: Facebook tribute page)
"Every time you walk past the house they would be barking and barking and going mad," she said. "You would jump out of your skin."
Jade was a pupil at Fred Longworth High School in Tyldesley, which open to help pupils affected by the death.
Headteacher Janet Garretts said: "We are all deeply shocked and saddened by Jade's tragic death. She had only been a pupil at the school since the summer but had made a real impact in that short time.
"Jade was a lively student who always had a smile on her face. She loved music and dance and was a regular at our after school dancing club.
"At what turned out to be her last day at school, Jade was given a progress report by her teachers and told everyone was delighted with the progress she was making."
More than 11,000 people joined a Facebook group created to pay tribute to Jade, including the aunt of a four-year-old boy who was killed by a banned breed of dog.
A policeman stands guard outside the house in Atherton, near Wigan
John-Paul Massey died at his grandmother's house in Liverpool after suffering "massive injuries" inflicted by a pitbull.
Tricia Massey wrote on Jade's page: "Such a tragic thing to happen. I know what your poor family must be going through and how they are feeling, I lost my four-year-old nephew three years ago.
"He was killed by a dangerous dog in Liverpool. Something needs to be done about these aggressive animals.
"Sleep tight Jade, I'm sure my John-Paul will look after you."
Natasha Hunt posted: "RIP my beautiful baby girl! Don't know what I'm going do without you!
"Love you loads, you will never be forgotten, you will always be in my heart."
Norman Bradbury, a local councillor, told Sky News the whole community was in shock.
He said: "We need to establish what occurred with this horrible incident and how it an be avoided in future but we have to wait for the police to investigate what happened, how Jade died and the circumstances."