"Heaven has gained a beautiful little angel and he will be greatly missed by us all and our other little soldier is still fighting strong."
The dog, which has since been put down, was owned by a serving police officer.
It is not known whether PC Clare Ferdinand, 31, was at the address at the the time the dog - believed to a Staffordshire bull terrier - attacked two children and a woman.
Essex Police refused to confirm that Mrs Ferdinand is employed by them though friends of the victims' family insisted she was.
A close family member, speaking from a house in Hornchurch, Essex, refused to comment on the dog attack.
He was too distressed to talk about the matter but a dog could be heard barking inside the property.
The horror unfolded at a home in Colchester, Essex, with the young boys' mother also being savaged by the dog.
All three with rushed to hospital shortly after yesterday's attack, and it is reported the mother was in the bath at the time.
The dog has since been put down with the owner's consent, police said, while the house is currently taped off as an investigation into the violent death begins.
John Ferdinand, 36, who owns the property and is the husband of PC Ferdinand, said: "There's no chance [of us commenting] at the moment. We will get in touch when we want to."
It's not yet clear whether the couple are related to the victims of Thursday's dog attack but it is thought that they have two young children.
Chief Inspector Elliot Judge said: "This is a tragic incident where a young child has lost his life.
"We can confirm the incident took place inside a house on Harwich Road, the dog has been destroyed, and no-one has been arrested.
"An investigation to establish the facts surrounding what happened is on-going.
"This is obviously a very difficult time for the family, who are being supported by specially trained officers."
Officers confirmed that the mother had been injured in the attack and had been discharged from hospital.
A post-mortem examination on the body of the four-month old baby is expected to take place late next week, while an autopsy of the dog is scheduled for this evening.
One neighbour witnessed a young boy in the ambulance after the attack took place. He said: 'I was walking past and I saw a young boy sat up in the ambulance.
"His face was covered in blood - it was shocking to see. He was in a bad way the poor little lad.
"I didn't actually know what had happened when I saw him. It was only later on that I found out.
"They'd not been living there very long and people round here didn't know them yet."
Scott Mills, who lives in a house opposite, became aware of "commotion" when he saw four police cars and two ambulances arrive at the family home on Thursday afternoon.
The 24-year-old said: "When we heard that a baby had died, everyone was very upset. It's dreadful and so tragic.
"There were a lot of children about because of the time - a lot of children were coming home from school."
Mr Mills believes the dog was a Staffordshire Bull Terrier-type dog, although the breed has not been confirmed by police: "I saw the dog being taken away.
"At 4pm a black van arrived. The dog was taken out of the property at 4.30pm. It was on a pole lead.
"It wasn't a normal Staffie. It was a lot more chunky - probably a Staffordshire cross or some kind of bulldog breed.
"No one opposite knows the family but I wish them the best at this awful time for them after a tragic accident."
Staffordshire bull terriers are not banned in the UK but are often mistaken for pit bulls, which aren't allowed by law.
The three other breeds to make the ban list are the Japanese Tosa, Dogo Argentino and Fila Brasiliero.
The man who owns the semi-detached, £300,000 property where the dog attack happened refused to comment on the incident.
A close neighbour recalled hearing a "loud bark" on the day of the horrific attack.
Thelma Monk, 79, was painting in her home, just a few doors down from the house where the attack happened, at around 3pm.
She said: "All I heard was a dog's loud barking. I haven't seen anybody come out of that house. I didn't hear any shouting."
Neighbour Dave Thompson said police backed into the drive to 'recover the animal' which he described as a dark brown "Staffordshire bull breed".
He said: "It was alive and not aggressive when they brought it out of the house and put it into the back of the van.
"It was quite big and I think it was a cross breed.
"Everyone had been pushed back by police and a woman came out of the house first."
Another close neighbour reports seeing the couple walking their dog, a type of Staffordshire bull terrier, in the local area.
He said: "They have only been living there up to a year. We rarely saw them. They kept themselves to themselves. They had a nice party the weekend after the August Bank Holiday.
"They had a dog. It was some sort of Staffy, pitbull cross. I only saw it twice, they did not walk it around here very often."
Speaking after the incident on Thursday afternoon, one neighbour, who wanted to be known only as Rachel, said: "It's quite scary especially when it's on your doorstep.
"I feel really sorry and my heart goes out to the people involved in it."
It is the second time in less than two months that a dog attack in Essex has led to the death of a youngster.
Colchester MP Will Quince has offered any support he can to those affected by the incident.
He said: "This is absolutely tragic. My thoughts and prayers are with the family at this most difficult time.
"I will, of course, give the family and authorities any support I can." A police cordon remains outside the home this morning.
A neighbour, who did not want to be named but was at home at the time of the incident, said: "The whole community is in shock. It's all very upsetting. You are caught off guard with these things.
"I am very upset about it all. My children saw it [the aftermath] and are very upset.
"We suddenly saw police cars at the house and the fact that it was two children is very upsetting. The little baby couldn't have done anything. It's just so sad.
"I didn't know the family well but you look out of the window and recognise your neighbours. I just can't believe it."
Dog welfare organisation, the Kennel Club, released a statement this morning about the incident in Harwich Road, which stressed any dog is capable of causing injury.
Caroline Kisko, club secretary, said: 'Our deepest sympathies go out to the family of the baby that was tragically killed and the child and adult that sustained injuries in this shocking incident.
"We don't have details of what happened in this specific case as yet so cannot comment on what may have led up to it, but we do know that incidents like this are thankfully very rare in the UK.
"When incidents like this do occur the focus is often wrongly on the breed or crossbreed of dog involved, rather than on the individual dog, and we would stress that any dog is capable of causing injury to a child, just as any dog can be a wonderfully loving pet that never shows any signs of aggression."
