Winnipeg police have confirmed that a body found in the Red River over the weekend is Lisa Gibson, the mother who disappeared after her two children were found fatally injured in the family's home earlier this week.

Police had been searching for Gibson, 32, in the area around the family's Winnipeg Westwood home since her three-month-old son and two-year-old daughter were found close to death in the bathtub at their home on Wednesday morning.

The two died after they were rushed to hospital.

Police put out a plea for Gibson to return home Thursday and began an intensive search. On Friday, they started diving the Assiniboine River near the family home after three people reported sightings of someone who looked like Gibson walking in pyjama pants and looking distraught.

Gibson's body was found Saturday just a few kilometres downstream from the home, past where the Assiniboine River joins the Red River.

Four teenagers from the provincial kayaking team, who were taking part in canoe races, saw it floating near the Alexander Docks.

Police considering postpartum depression

Dozens of police officers had taped off a wide area along Waterfront Drive within minutes. They used a tarp to shield the scene as the coroner examined the body and wheeled it away.

The teens who found the body are being offered counselling.

In a news conference Sunday, police said an autopsy has been completed on Gibson and her two children but they are not releasing the results. They said officers with the homicide unit are continuing their investigation into the deaths of all three.

"There's been lots of speculation as to the cause of the incident," said Const. Eric Hofley. "Investigators do not have that luxury, they have to investigate all possible avenues to determine the cause."

Hofley said the past few days have taken their toll on officers and other emergency workers.

"You know there is this expectation that emergency personnel are professional at the time and absolutely that's what we're trained to do," he said. "Having said that, we are human, and this type of tragedy will affect people in different ways."

Police said postpartum depression is one of the factors they are considering, but they would not comment on the mental state of Lisa Gibson before her death or speak about how her husband is doing.

The Winnipeg Regional health authority said it is reviewing what contact Lisa Gibson may have had with the health care system.

Hofley said Gibson's family was requesting privacy.

Memorial continues to grow

A makeshift memorial for Gibson and her children has been set up in the corner of the family's yard.

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A makeshift memorial has been set up outside the Gibson home in Winnipeg. (CBC)

People began depositing stuffed animals, flowers and notes on Wednesday, and the pile continued to grow through the weekend.

On Sunday, people visiting the memorial said they did not know how else to express their emotions about the deaths.

"It's just sad, all around it's just a terrible situation," said Vikki Ladd, who came with her sister Aveleigh and niece, Emily.

"It's terrible, it's a tragedy," added Aveleigh Ladd, as her daughter placed a stuffed Smurf on the pile.