A van driver accused of killing 10 people in Toronto posted to Facebook minutes before the attack to praise killer Elliot Rodger and refer to the misogynistic "incel" Reddit group.
Alek Minassian, 25, was charged on Tuesday with 10 counts of murder and 13 counts of attempted murder.
Police say he appeared to intentionally strike pedestrians after mounting a busy pavement in a rental van.
He was arrested several streets away after a tense standoff with police.
The 10 dead and 14 wounded are "predominantly" women, ranging in age from their twenties to their eighties, police say.
Canadian Prime Minister Justin Trudeau called the incident a "senseless attack and a horrific tragedy".
The suspect's Facebook post, which the social network has confirmed as real, praised Elliott Rodger, a 22-year-old from California who killed six people in a shooting rampage through Isla Vista, California in 2014 before turning the gun on himself.
It read: "The Incel Rebellion has already begun! We will overthrow all the Chads and Stacys! All hail the Supreme Gentleman Elliot Rodger!"
The term "incel" refers to a now-banned group on the message site Reddit, used by Rodger, where young men discussed their lack of sexual activity and attractiveness to women - often blaming women for the problem.
"Chads and Stacys" refers to attractive men and women who are perceived as better than or unavailable to "incels", which is short for "involuntary celibate".
He was brought to court on Tuesday to hear the charges against him.
His head shaved and wearing a white jumpsuit, he held his hands behind his back, showing little emotion throughout.
He will remain in custody and return to court on 10 May for a bail hearing. He was ordered to make no contact with surviving victims.
A man believed to be his relative sat in the front row of the courtroom and wept. Asked by reporters if he had anything to say, the man replied, "Sorry".
Yonge Street, where the attack took place, remained closed on Tuesday as police continued their investigation.
While the authorities have not yet formally identified any of the dead, three have been named in the media.
Anne-Marie D'Amico worked for the US investment company Invesco, Canadian broadcaster CBC reports. The company's Canadian headquarters are on Yonge Street.
The Jordanian embassy in Ottawa has told the BBC that one of its citizens was among the victims. Jordanian media named him as Munir Abdo Habib al-Najjar who, they said, was in Canada to visit one of his sons.
Toronto resident Dorothy Sewell, 80, has also been named by relatives as one of the victims.
Dorothy Sewell was a fan of the Toronto Blue Jays baseball team
Her grandson, Elwood Delaney, said she was the "best grandma anyone could have asked for".
The South Korean embassy in Canada confirmed to the BBC that two of its citizens were among the dead and another was critically ill. Their names have not been disclosed.
The 15 injured remain in hospitals throughout Toronto.
From the northern Toronto suburb of Richmond Hill, he was not previously known to the authorities as an offender.
There "would appear to be no national security connections", public safety minister Ralph Goodale said.
He attended a school for students with special needs in north Toronto, former classmates say.
He would be seen walking around Thornlea Secondary School with his head down and hands clasped tightly together making meowing noises, Shereen Chami told Reuters news agency.
But she added that he had not been violent: "He wasn't a social person, but from what I remember he was absolutely harmless."
He went on to attend Seneca College in the North York area of Toronto, where the van incident took place, CBC reports.
The Canadian Armed Forces (CAF) has also confirmed he was a member for two months in late 2017 before asking to be voluntarily released.
Police say the suspect in the van mounted the kerb on Yonge Street between Finch Avenue and Sheppard Avenue at about 13:30 local time (17:30 GMT) on Monday and drove into pedestrians along a 1km (0.6-mile) stretch.
Reza Hashemi, who owns a video shop on Yonge Street, told the BBC he had heard screaming on the other side of the road. He said the van had repeatedly mounted the pavement, running into people.
One witness told City News the driver had hit "anything that comes in the way".
"People, fire hydrants, there's mail boxes being run over," said the unnamed man, who said he was driving behind the van during the incident.
As the van continued, the man said he had sounded his horn to try to warn pedestrians. "I witnessed at least six, seven people being hit and flying in the air, like killed, on the street," he added.
Pictures from the scene show bodies covered in orange sheets along the van's route. Debris and items of clothing were scattered across the pavements and road.
The suspect confronted a police officer and claimed to have a gun
The van was brought to a halt by police several streets away and was quickly surrounded.
The suspect pointed an object at an officer and claimed to have a gun, to which the officer replied, "I don't care. Get down."
He then arrested the suspect without firing a shot. The arrest was filmed by two bystanders and the officer was praised for not opening fire.
A makeshift memorial has sprung up at the junction of Yonge Street and Finch Avenue and a wall is being filled with messages of condolences, grief and support.
One of those who came to lay a flower, Dave Spence, said residents would "walk a little differently" when they came through the area "for years to come".
Flowers and messages are left near a small park on Yonge Street