CREDIT: The Canadian Press Andrea Labbe holds her children Brigitte (left) and Zoe in this photo taken on Mother's Day, 2003. Police say Ms. Labbe stabbed her husband, Brian Langer, 47, as he lay in bed, before stabbing Brigitte and Zoe. Zoe died, Brigitte survived and a third daughter, seven-month-old Margot, was unharmed.

TORONTO - A mother of three fatally stabbed her husband before slashing two of her children's throats, killing her three-year-old daughter, police said yesterday.

Andrea Labbe, 26, then bypassed a bedroom where her seven-month-old daughter was sleeping, went downstairs and cut her own throat.

Det. Sgt. Chris Buck, the lead investigator in the case, said, "We now know the 'hows'. We know the 'whos'. We don't have all the answers as to the 'whys' and we may never have all the answers to the 'whys'.

"There are no good answers for the families."

At a news conference at Toronto police headquarters, Det. Sgt. Buck said he wouldn't comment on reports that Ms. Labbe had sought professional help in the days before the killings and refused to confirm whether investigators were searching for any of her medical records.

"The investigation from that angle will continue," he said. "But that is a matter of family privacy and I'm not going to discuss that. I will not be disclosing the details of anyone's medical records."

He did confirm that Ms. Labbe had mentioned to friends that she was tired and stressed by the demands of caring for three young children, but wouldn't say whether police are looking into postpartum depression or postpartum psychosis as a possible explanation for the tragedy.

Police arrived at a home in Toronto's west end earlier this week to find Ms. Labbe dead in a pool of blood, her husband Brian Langer, 47, bleeding profusely from a stab wound to his stomach and two of their three young children with knife wounds to the neck.

Mr. Langer and his daughter Zoe, three, died in hospital. The two-year-old toddler, Brigitte, underwent emergency surgery at Toronto's Sick Kids Hospital where she was listed in stable condition yesterday.

Seven-month-old Margot Langer was the only member of the family to escape injury. Ms. Labbe even attacked the family dog.

Det. Sgt. Buck wouldn't give details of exactly what happened inside the family's home, but one police source, speaking on condition of anonymity, said Ms. Labbe is believed to have stabbed her husband while he lay in bed, then gone into

the room shared by her two toddlers and slashed their throats.

Although mortally wounded, Mr. Langer managed to make it to a telephone in the couple's bedroom and call 911. Ambulances and police were on the scene within minutes.

Staff Insp. Jeff McGuire, head of the Toronto police homicide unit, said the horrific crime scene was one of the most difficult his officers have ever had to deal with.

"Pretty much everyone here has kids, so it's difficult," he said. "Some of the cases, you just have to get used to unfortunately. But certainly when it's young children -- completely innocent -- involved, then it tears up the heart."

Staff Insp. McGuire said crisis counselling has been offered to the officers involved in the case.

Det. Sgt. Buck said the baby was being cared for by relatives and that when Brigitte was released from hospital she would be taken in by one of her parents' extended families.

"The families are now in the process of preparing for three funerals," he said. "They are all grieving together. ... We need to let these families get on with their lives."