One woman was killed and five others wounded after being stabbed at a public library in a Vancouver suburb on Saturday.
Canadian police told local media they had the lone suspect in custody, though the motive remains unclear.
They added that the suspect had a past criminal record.
Video from the scene reportedly appeared to show a man injuring himself with a knife before being taken into police custody.
Investigators are now appealing to witnesses of the attack, which occurred in the early afternoon at the Vancouver North Library.
Drone footage showed Emergency Health Services aiding the wounded.
No further details of the victims were provided.
In responding to the incident, Prime Minister Justin Trudeau said on Twitter, "My heart is in North Vancouver tonight. Know that all Canadians are keeping you in our thoughts and wishing a speedy recovery to the injured."
North Vancouver is a mostly quiet and wealthy suburb of about 85,000 people.