Chuang (Ray) Li, 47, faces three counts of attempted murder, four counts of aggravated assault and four counts of assault with a weapon.
Police say Li worked in the IT department of human resources company Ceridian. Police say the company was in the process of firing Li when he attacked his co-workers.
Police responded to calls of multiple stabbings just after 9:30 a.m. ET Wednesday in the fifth floor an office building at 4110 Yonge St., near York Mills Avenue. Police said 911 callers heard reports of an assailant attacking people in the office with "a sharp instrument" they believed may have been a knife.
Three men and one woman were sent to hospital with injuries following the attack. Three were still there by early evening. The woman, who is 32, was still in critical condition by late Wednesday evening. Two of the men have less serious injuries, police said.
Initial reports indicated the males are between the ages of 35 and 45.
Li, who was not injured in the attack, was subdued by employees until officers arrived.
Yesterday afternoon, a statement from the company said "the entire Ceridian family is shocked and deeply saddened by this incident."
Li's Mississauga neighbours are having a hard time imagining him on a rampage with a knife. They say Li was quiet, always friendly and never did anything out of the ordinary.
Shelly Brooks lives next door.
"He was always a good neighbour and they're nice people so I don't know what to think about it," said neighbour Shelly Brooks.
Nicknamed Ray, Li lived with his teenage daughter, wife and the family's small dog on a quiet residential street.
William Sadora lives a few doors down from the Li family.
He says the family has been in the area for nearly a decade. Sadora often saw them on evening walks.
"It's shocking you know, especially when it's just a couple of doors down."
Li's wife and daughter were too distraught to speak. Both are asking for privacy.