Two teenagers charged and two arrested in connection to the stabbing death of a 14-year-old boy outside his school in Canada

A 14-year-old boy was stabbed to death outside Sir Winston Churchill Secondary School in Hamilton, Ontario, Canada Monday.

(CNN)Two teenagers have been charged with first degree murder, and two more were arrested Tuesday in connection with the stabbing of a 14-year-old boy outside a school in Ontario, Canada, police said.

Hamilton police identified the slain teenager as Devan Selvey, a student at Sir Winston Churchill Secondary School in Hamilton, about 50 miles west of Niagara Falls.
A 14-year-old boy and an 18-year-old boy were charged and appeared in court. On Tuesday morning, a 16-year-old boy and a 16-year-old girl were also arrested, police said.
The two 16-year-olds remain in custody as authorities investigate their involvement, Hamilton police said.
    Police believe they've located the murder weapon after conducting a ground search of the homicide scene, Det. Sgt. Steve Bereziuk said in press conference.

    His mother witnessed the stabbing

    Selvey was stabbed Monday and his mother witnessed the assault, Bereziuk had said earlier.
    She was not harmed in the incident, Bereziuk said. He wouldn't comment on why the mother was in the area at the time of the stabbing.
    "She's witnessed something horrible here," Bereziuk said. "She is distraught."
    Bereziuk said that authorities have video of the incident.
    Bereziuk said police believe there was a relationship between the suspects and the victim, although he wouldn't elaborate on what that relationship was.
      "I mean, I think when I look at this so far, it's a complete disregard for human life which is extremely concerning for people of such a young age," he said.
      In Tuesday's press conference, Bereziuk said he wouldn't speak to the possible relationship between the accused and the victim. He would not say bullying was involved, but confirmed it is something they continue to investigate.