"A four-year-old boy has been mauled to death by a dog at a family home in Liverpool.
The child, who the BBC has learnt was called John Paul Massey, was attacked at the property in Ash Grove, Wavertree, just after midnight.
A 63-year-old woman was also injured and is being treated in hospital. It is believed she was hurt as she separated the dog from the child.
Merseyside Police said armed officers killed the animal in the front garden.
Dog handlers also attended the scene and an investigation has begun. Efforts are continuing to identify the dog's breed.
Ch Supt Steve Ashley said: "This is a tragic incident and a full and thorough investigation will be carried out into the circumstances surrounding this young boy's death.
"Officers are with the family and our sympathies are with them at this time."
He added: "Of utmost importance in such incidents is the safety of the public and of police officers. "When officers arrived at the address the dog was in an agitated state in the front garden of the property and was deemed to be a danger to the public.
"As a result we were left with no other option but to have the animal destroyed quickly and humanely."
On Monday morning, police tape surrounded the house and street where the boy was attacked.
Local parish priest Father Peter Morgan, of St Anne's Church in Edge Hill, emerged from the house on Monday afternoon after meeting the family.
He said: "There is an awful lot of pain inside... They are broken, it is so, so sad."
The BBC's North of England correspondent, Nick Ravenscroft, said the youngster's identity was confirmed by the head teacher of St Clare's Roman Catholic Primary School in Wavertree.
People spoke of their shock at the death but complained there had been a problem with so-called dangerous dogs in the area.
Gillian Watson, 46, who heard the gunshot that destroyed the dog, said: "It's such a terrible thing to happen to a family.
"There are lots of dangerous-type dogs around here. You always see young lads with pit bull dogs roaming around.
"I have a dog myself and when I take him for a walk sometimes it's quite terrifying because you think your dog is going to be attacked."
Another neighbour, who did not want to be named, said residents had complained to the local Housing Association about the problem.
He said: "You see them all the time, they're huge animals and it is very threatening."
The attack comes nearly three years after the death of Ellie Lawrenson, a five-year-old killed by her uncle's pit bull terrier on New Year's Day 2007, just a few miles away in St Helens.
Merseyside Police held a dangerous dogs amnesty after her death in which more than 80 illegally-held dogs were seized."How are pit bulls in any way relevant to this case? They had the decency to admit that the dog's breed hadn't yet been identified (I dunno, chief, whaddya think he looks like?) That being said, how did they attempt to loosely string together the rationale that pit bulls were somehow magically responsible for this? I am so sick of seeing inane comments like "I take my dog for walks and I'm afraid he's going to be attacked." What does that have to do with pit bulls? Any dog off leash may be inclined to attack the dog you're walking. If you allow your dog to get close enough to an aggressive, leashed dog that it attacks then it's nobody's fault but your own. This possibility has absolutely nothing to do with any specific breed of dog. They mention neighbors being concerned with "so-called dangerous dogs" which as evidenced by the remainder of the article is purely a reference to pit bulls. Not to dogs actually displaying aggressive behavior like the one who killed this little boy. The circumstances of the attack are hardly mentioned in the article. The only descriptors of the dog are that it was in an "agitated state" and that it was in the front garden. We don't even know if it was a loose dog, for all we know it could have been that the boy entered someone else's fenced front yard and the dog killed him. In which case, how can we place responsibility on the dog over the caretaker of the child who allowed this to happen? Regardless, you can't make any judgment with information that is this vague. I will never understand how people are able to redirect their attention from the the issue at hand to the completely unrelated idea of "aggressive breeds" that were not even involved in the attack! You can start your unfounded mud-slinging when the dog is "identified" as a pit bull, and not a moment before. Also interesting to note that they failed to mention that the number of dog bites in Britain has tripled since they passed the Dangerous Dogs Act in 1991.