ST.CATHARINES, Ont. – Police in Ontario's Niagara region said Sunday that a 43-year-old man was wanted for first degree murder in connection with the death of his stepson.

Justin Kuijer's seven-year-old stepson Nathan Dumas was found critically injured in a residence on Queenston Street in St. Catharines Friday morning. He was rushed to hospital, but died early Saturday. Police did not immediately reveal the cause of death.

Kuijer, 43, was already wanted in connection with a stabbing that also occurred Friday. Police allege Kuijer entered a Royal Bank branch, stabbed a female employee, and fled in a van.

Police said the incident was not a robbery, and that Kuijer and the woman knew each other professionally. The woman was in stable condition in hospital.

Niagara Regional Police Const. Philip Gavin said a Canada-wide warrant was to be issued on Monday for Kuijer for first-degree murder and for attempted murder.

Because he has a vehicle, Gavin said Kuijer could be far from the Niagara region.

"We don't know his whereabouts," he said.

Gavin also said this case has been a hard one for police to deal with.

"A situation like this, it impacts the community, it impacts the family," he said. "It's not easy, but we have a job to do, and we try to persevere through that."

Police said the suspect was considered armed and dangerous. They say members of the public should not approach him and call 911 immediately.

Friends of Nathan Dumas' family started a GoFundMe campaign to help pay for funeral costs. The campaign had surpassed its $10,000 goal as of late Sunday afternoon.

"He was the most loving and caring little boy," the page reads. "And now because of another he will never be able to grow into a fine young man and make a diff(e)rence in this cruel world."

Kuijer was last seen wearing an orange hoodie under a brown leather coat, dark pants, a black toque, and boots, police said. There is a pink floral decal on the back window of the dark grey van he was driving that references missing person Ashley Simpson and "Missing Women of Canada."

The suspect van's licence number was BYTE392, police said.