A two-year-old boy has died — the same day his eight-month-old sister was buried — after they were exposed earlier this week to a pesticide used to kill bedbugs.

Zia Hassan died in hospital in Edmonton Thursday, after he and four siblings were sickened by phosphine in his family’s Fort McMurray, Alta., apartment.

The eight-month-old, Zara, died Monday. The family held her funeral in Edmonton Thursday afternoon.

“The family is devastated,” said Fort McMurray member of the legislature Mike Allen, who was at the funeral.

“No parent should have to bury their child. This is a very tragic loss, to see such a tiny little casket.”

A third sibling, a six-year-old boy, remains at the Stollery Children's Hospital in Edmonton on a ventilator.

Two other children, aged four and seven, were released from a hospital in Fort McMurray on Wednesday. Their mother, who was in hospital under observation, has also been released.

Following the funeral, the principal of the school the two eldest children attended said the family is trying to deal with the tragedy.

“Think about this family in your prayers and if possible, help them,” said Taj Mohammed.

“Support them somehow that you feel correct.”

He said the two oldest children will be returning to school Monday, and that counsellors will be available to help them come to terms with what happened.

“We will try to do our very best to make them understand,” he said. “It's tough, it's not easy.”

Phosphine illegally imported

The insecticide was brought into Canada from Pakistan illegally to fight a bedbug infestation, said the children’s aunt Shazia Yarkhan.

Firefighters said they found an unmarked container within the home containing phosphine.

When mixed with water, it creates a deadly gas. Experts told CBC News the family was likely breathing the gas for several days before the children fell ill and that the children may have been more affected by the gas.

The pesticide use appears to have been isolated to the one apartment, RCMP have said.

A funeral for the boy will be held Friday.

About phosphine: