Police say more than 100 tips have poured in from across Canada as investigators hunt for an Ontario man who allegedly killed his seven-year-old stepson and stabbed a bank employee.

Police issued a nationwide warrant for 43-year-old Justin Kuijer after receiving judicial authorization on Monday afternoon.

A resident of St. Catharines, Ont., Kuijer is wanted on charges of second-degree murder in the death of his seven-year-old stepson, Nathan Dumas, and attempted murder in connection with an attack on a bank employee.

Late Monday night, Niagara Regional police released a statement saying investigators were “working with local police” following an unconfirmed sighting of Kuijer in Port Severn, Ont. Port Severn is located approximately 251 kilometres north of St. Catharines.

Niagara Regional Police Const. Phil Gavin word of possible sighting in Port Severn began to surface over social media.

“We’re certainly working with our local law enforcement agencies in that area to try and get some more information about it but at this point, it’s unconfirmed,” Gavin said in an interview on CTV News Channel Tuesday morning. “We can’t 100 per cent say that that was Justin Kuijer near Port Severn.”

Niagara police are asking the public to be “vigilant and report information or possible sightings” of Kuijer, who is considered armed and dangerous.

The police manhunt for Kuijer began on Friday, when a man entered a Royal Bank of Canada in St. Catharines and stabbed a female employee. The woman was rushed to hospital, where she is believed to be in stable condition. As police responded to the stabbing, officers were also called to a home in the city, for a seven-year-old boy who was in medical distress.

Police allege Kuijer attacked Nathan on Friday morning, causing undisclosed injuries. Nathan died in hospital on Saturday.

On Monday afternoon, Niagara Regional Police confirmed that they had received judicial authorization for a Canada-wide arrest warrant for Kuijer.

Police say Kuijer is the stepfather of the young boy and had a professional relationship with the bank employee who was stabbed.

Ontario Provincial Police and Canada Border Service Agency have been notified because the suspect is believed to have access to a vehicle, and may have crossed into the United States.

“With access to a vehicle, he really could have put significant distance between here and Niagara region,” Gavin said.

The constable added that the last known contact anyone had with Gavin, he had access to the vehicle, so “having not found the van, we’re working on the premise that he still has it.”

Police have said Kuijer was last seen wearing an orange hoodie under a brown leather coat, dark pants, a black toque, and boots. He was driving a 2009 dark grey Pontiac Montana van with a floral decal on the rear driver’s side window. The decal references the name Ashley Simpson and “Missing Women of Canada," but it is not related to the case. The suspect van's licence number was BYTE392.

Gavin said finding the van could be “key” to the investigation and police are asking the community to keep an eye out for the vehicle and phone 911 immediately if they spot it.

Slain boy remembered as kind, polite

As police continue to search for the suspect in Nathan Dumas’ death, the young boy was being remembered by his family as loving, polite and compassionate.

In an obituary, Nathan’s family described him as a caring, considerate boy who never missed an opportunity to come to the defence of a friend.

“Our family will forever cherish the fond memories he brought to us,” the obituary read. “Nathan was a truly kind, loving boy with a big heart, full of compassion for everyone and everything.”

The obituary went on to say that there are “no words to express the unbearable heartbreak we feel in his loss."

On Tuesday, school officials told CTV Toronto that students at Harriett Tubman Elementary School, where Nathan attended Grade 2, were writing down their favourite memories of Nathan.

Their tributes will be placed in a memory box that will be presented to the family.

A memorial with flowers and teddy bears continued to grow outside Nathan’s family home. A funeral will be held Friday for Nathan in St. Catharines.

With files from CTV Toronto’s John Musselman and The Canadian Press