RCMP Staff Sgt. Bill Richat said the boy's grandmother was also injured as she tried to beat the dogs -- large cross-breeds -- off her grandson.
The boy was rushed to the town's nursing station, but was later pronounced dead.
Richat said the attack happened at about 2:30 p.m. as the boy played with a small puppy near the house. He was also eating a piece of bannock.
The four dogs were tied up near the house in a bushy area and somehow broke free of their rope and chain restraints.
One dog tried to get the bannock from the boy and, in the ensuing tussle, a second dog attacked the boy, with two more quickly getting involved.
The dogs were later shot by police and are to be tested for rabies.
Richat said only the grandmother witnessed the attack. The boy's name will not be released until all his family is told of his death.
This is the second tragedy in Nelson House in two weeks.
Rachel Lori Wood, 22, hung herself in a cell Oct. 5 after she was arrested by band auxiliary constables for being intoxicated in public.
Area residents said there were a number of dogs on the property, located on what's known as R.C. Point, that were being kept as pets. Nelson House (Nisichawayasihk Cree Nation) is about 810 kilometres north of Winnipeg.
Chief Jerry Primrose said the community is mourning.
"This is a terrible tragedy," he said in a statement. "I had the sad task of informing the family of the death of their child and it has been one of the hardest things I have ever had to do. They are understandably devastated by this accident and the whole community is struggling with this loss."
Primrose added that the community has a long-standing bylaw that prohibits dogs from running loose.
The last fatal dog attack in Manitoba happened Dec. 21, 1998, when a pack of wild dogs killed an eight-year-old boy on the Cross Lake First Nation. Two years earlier, a three-year-old boy was similarly mauled to death on the same reserve by a pack of four stray dogs. Cross Lake is 780 kilometres north of Winnipeg.
Fatal dog maulings are rare in Canada, but can happen when domestic dogs "pack up" and instinctively attack wildlife, children or even adults.
Some northern communities shoot wild dogs once or twice a year to lessen the chances of people being attacked.
Vicki Burns, executive director of the Winnipeg Humane Society, said since the last attack in Cross Lake the non-profit agency has offered subsidized mobile spay and neuter clinics for isolated communities.
The humane society now goes up to Churchill and Norway House twice a year to "fix" pets.
She added that, in the absence of dog-control bylaws, some communities have no choice but to shoot wild dogs. In some instances, these dogs can breed with wolves and pose a greater danger.
"What happened is really heart-breaking," she said. "But there are options if the communities are interested."