Hundreds of mourners bid an emotional goodbye to a mother and her three children who died after flames ripped through their family home in Alexandria last week.

One casket carrying Sarah Cholette, 22, and her three kids was brought into Sacre-Coeur Church on Alexandria's Main Street late Friday morning. All four will be buried together.

Even the parish priest, who has dealt with several tragedies over the years, broke down when describing his emotions.

"I went earlier than the announced time so that I would have the family with me before the crowds were really coming in, so I would have a chance to say the prayers in front of the coffins. So, that was very difficult because you see these young children in there and it's very hard," Father Denis Vaillancourt told CTV Ottawa, his voice quivering.

Cholette and two of her children – three-year-old Chloe and baby Jacob – died in the blaze last week. A third child, 19-month-old Maxime, died a few days later in hospital.

"There is no word to describe," said relative Lorraine Seguin. "It's like a living hell that I wish I could just wake up from. But it's not going to happen."

The children's father, 26-year-old Martin Desjardins, remains in an induced coma in critical condition in the burn unit of a Toronto hospital.

It was left up to his family to write how he might have said goodbye to the rest of his family.

"Goodbye my loves, goodbye my angels," said the note, which was read at the service. "Daddy will always have you in his heart."

Family members say although they've had a week to wrap their heads around the tragedy, Desjardin will only learn about it when he wakes up.

"Us, we've been familiar (with) this for week now. He doesn't even know anything yet," said Mark Cholette. "It's going to be a nightmare and a shock when he wakes up and his wife is gone and his three kids are gone."

Investigators say the fire started on the porch of the home, blocking the family's only exit.

Ontario's fire marshal's office has also determined there was no battery in the second-floor smoke alarm near the bedrooms. There was a working smoke alarm on the first floor.

Relatives say the support from their community has been very much appreciated over the past week, with a number of businesses taking donations for the family.

Anyone wishing to make a donation is being asked to donate to the Children's Hospital of Eastern Ontario, where doctors fought hard to keep Maxime alive. He passed away in hospital on Monday.

With files from CTV Ottawa's John Hua