Charges have been laid against a Mississauga man accused of stabbing his former co-workers in a north Toronto office building.

Chuang (Ray) Li, 47, faces charges including three counts of attempted murder and four counts of aggravated assault.

The attack happened just after 9:30 a.m. ET on the fifth floor of an office complex at 4110 Yonge St., near York Mills Avenue.

Three men and one woman — employees of a human resources company — 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.

Police received numerous 911 calls Wednesday morning about an assailant attacking people with "a sharp instrument" they believed may have been a knife.

The suspect was subdued by employees until officers arrived.

That afternoon, a statement was issued by Ceridian, the parent company of Dayforce, whose employees were attacked.

"At approximately 9:30 a.m. today, four Ceridian employees were attacked by a former employee at our Toronto office," said the statement from Ceridian CEO David Ossip and president Dave MacKay.

Toronto police stand outside an office building in the city's north end following a stabbing on Wednesday morning. (Nathan Denette / Canadian Press)

While Ceridian did not identify the suspect or the wounded employees, the company said "the entire Ceridian family is shocked and deeply saddened by this incident."

The suspect was not injured in the incident. Footage from outside the office building showed a man wearing a striped blue office shirt and dress pants being led into a police cruiser.

Later Wednesday, police were seen towing a vehicle from the garage of the building.

Li is due to appear in court Thursday morning.