Alek Minassian was born on November 3, 1992, in Canada. His father, Vahe, moved to Canada from Armenia and worked as a software developer. His mother, Sona, was from Iran and had a job at an IT company called Compugen Inc. Alek showed an interest in technology from a young age and aspired to be a software and mobile app developer.

Alek's early schooling took place at Sixteenth Avenue Public School, where he attended special education classes. Later, he went to Thornlea Secondary School in Thornhill. Classmates remembered him as "not overly social" and "harmless." At Thornlea, he was part of a special needs class for students on the autism spectrum. In 2009, his mother mentioned that Alek was diagnosed with Asperger syndrome.

From 2011 to 2018, Alek attended Seneca College in North York. He lived in Richmond Hill during this time. In late 2017, he briefly enrolled in the Canadian Armed Forces. However, after just 16 days of training, he requested to leave, not adapting well to military life. A senior military official noted that there were no signs to predict his future actions.

On April 23, 2018, at approximately 1:22 p.m., Alek Minassian carried out a violent attack in Toronto. He drove a rented white Chevrolet Express van down the west-side sidewalk of Yonge Street, starting at Finch Avenue. He ran a red light and began striking pedestrians as he drove south.

The van continued on the sidewalk for several blocks, hitting numerous people. Security cameras captured the van reaching Tolman Street at about 1:24 p.m. During the incident, the van briefly re-entered the road due to narrow sidewalks before returning to the sidewalk at Park Home Avenue. It struck more pedestrians outside Mel Lastman Square, which is about 1.4 kilometers south of where the attack began.

The first 9-1-1 call reporting the attack was made at 1:25 p.m. Paramedics were quickly dispatched to the scene, and an emergency center at Sunnybrook Health Sciences Centre was activated.

Officers from the Toronto Police Service responded to the scene. A police constable, Ken Lam, intercepted the damaged van about 2.3 kilometers south of the starting point of the attack. Minassian was standing near the driver’s side door. During the confrontation, he reached into his back pocket and pointed an object at Lam, prompting the officer to order him to drop to the ground. Minassian demanded to be shot. Eventually, he dropped the object and surrendered to Lam. He was arrested at 1:32 p.m., just ten minutes after the first distress call.

The attack resulted in the deaths of eleven individuals, with nine fatalities occurring at the scene. Later, a tenth victim died that evening, and an eleventh succumbed to injuries in 2021 after being paralyzed. Additionally, fifteen others were injured during the incident. Minassian's actions were motivated by personal beliefs linked to the "incel" community, which focuses on frustration over perceived rejection by women. He was charged with ten counts of first-degree murder and sixteen counts of attempted murder.

Following the incident, the area was cordoned off for investigation. Public transport services nearby were closed or adjusted, and additional security measures were implemented.