A man accused of stabbing four employees at a north Toronto office building appeared in court Thursday.

Chuang "Ray" Li, 47, from Mississauga, Ont., faces three counts of attempted murder, four counts of aggravated assault, and four counts of assault with a weapon.

On Wednesday, officers were called to the Yonge Street offices of Ceridian Canada just after 9:30 a.m., after reports of a man attacking his co-workers with a sharp implement.

A man and woman in their 30s were rushed to hospital with life-threatening injuries and remain in critical condition. Two other men were also injured in the attack. Police said one man has been released from hospital while the other remained hospitalized overnight for observation.

According to Det. Dan Darnbrough, the two victims currently in critical condition were believed to be the attacker's superiors and were in the process of firing him when they were stabbed.

Police said the two victims with less serious injuries allegedly tried to subdue the suspect during the attack.

In a statement released Wednesday afternoon, Ceridian said the attacker was a "former employee."

"Our thoughts and prayers are with the victims and their families. As you might imagine, this is a very difficult time," the company's chief executive officer David Ossip, and Dave MacKay said in a statement.

"Out of respect for the privacy of the individual and their family, we are not able to share or comment on the specifics of the individual's condition but all four employees are being treated by medical experts at area hospitals."