The St. Catharines, Ont., woman whose seven-year-old son was killed is asking for "privacy and space" as she mourns the "loss of my beautiful son."

Nathan Dumas was found injured at a home Friday and died in hospital the following day. A Canada-wide warrant was issued on Monday afternoon for the man wanted in connection with his death.

The boy's exact cause of death hasn't been released.

Police in Ontario's Niagara region said Sunday that Justin Kuijer, 43, is wanted for second degree murder in connection with the death of his stepson. (Niagara Regional Police Service)

His mother, Whitney Dumas, wrote a note on Facebook Sunday: "Your kind words and well wishes and downpour of donations have been truly overwhelming. Our Niagara regional police are truly something to be proud of. They have gone above and beyond the call of duty with support and compassion."

A gofundme page has been set up to take donations in support of the Dumas family, and it sat at over $12,500 as of Monday afternoon.

"He was the kindest little boy you'd ever meet. Everybody loved him," Dumas said in an interview with the St Catharines Standard. "He was such an old soul."

Visitation will be held Thursday and Friday at Pleasantview Funeral Home with the funeral scheduled for Friday at 2 p.m at the funeral home chapel.

In keeping with his family's wishes, cremation will take place following the service.

Bank employee stabbed

Niagara Regional Police searched for the 43-year-old suspect, Justin Kuijer, through the weekend after a female bank employee was stabbed Friday at an RBC branch on Martindale Road in St. Catharines.

Police say Kuijer is the stepfather of Nathan Dumas and is armed and dangerous. Niagara police spoke to the media at 8 a.m. Monday morning.

The apartment where Nathan Dumas was found before being brought to hospital. (Adrian Cheung/CBC)

The warrant being issued is for second-degree murder in the case of the boy and attempted murder in connection with the stabbing of the bank employee, who is in hospital in stable condition.

Nathan died Saturday after being discovered in medical distress in St. Catharines on Friday. Police said he was transferred to hospital in critical condition from his home on Queenston Street. Const. Phil Gavin with the Niagara police told CBC they "consider [Kuijer] responsible for his death."

Police are looking for a man after he allegedly attempted to kill a woman at a St. Catharines Royal Bank branch. Police now report the man is wanted for murder in the death of his stepson. (Dave Ritchie/CBC)

Police said Whitney Dumas "is co-operating with [the police] and [they] have taken security measures to ensure her safety."

"She is also grieving at a terribly tragic situation at the loss of a son in a way that few people could comprehend," Gavin said. "It's a terrible situation for her. She's working with us."

Nathan was a student in Grade 2 at Harriet Tubman Public School on Henry Street in St. Catharines.

"The community is upset and grieving," said Kim Yielding, a spokesperson for the District School Board of Niagara.

"The principal of the school has been in touch with the family to let them know we're here for them," she said.

<a href="https://twitter.com/hashtag/RBCInc?src=hash">#RBCInc</a> 13. Further information just in. The vehicle involved is dark grey in colour. Please see photo. If you see call 911 <a href="https://t.co/AuxcMymDTB">pic.twitter.com/AuxcMymDTB</a> —@PCPhilGavin

"We have social workers at the school at the moment," said Yielding. "They are there to support students, and the staff too. Teachers will be speaking to their students in age-appropriate ways, and social workers will be on hand."

"We do believe the victims were targeted," Gavin told reporters on Sunday. Police didn't disclose the connection between the attack on the woman at the bank and the death of the boy. Police said the woman and Kuijer are "known to each other professionally" but did not elaborate.

Police originally reported the stabbing as an assault of an employee at an RBC branch.

Initially treated at the St. Catharines site of the Niagara Health System, the woman was transported to a trauma centre outside of the Niagara region.

Police said the man fled in a grey 2009 Pontiac Montana van, licence plate BYTE392. The van also had a pink-and-white decal in the back window for missing woman unrelated to the case.

Justin Kuijer is shown in a Niagara Regional Police Service handout photo. Niagara police are on the hunt for Kuijer, a 43-year-old Ontario man wanted in connection with a stabbing at a bank and his stepson's death. (Handout/Niagara Regional Police Service)

"Where he may be going we just don't know," Gavin said Monday.

Kuijer is described as a white male with a tall, thin build, with a beard and longer dark hair. He wore a black tuque and coat, boots and possibly an orange sweater.

Anyone who sees the van, or has information, should call (905) 688-4111 or Crime Stoppers at 1-800-222-8477.

"Should a member of the public observe or know the location of Justin Kuijer, do not approach him," police said.