The Special Investigations Unit is looking into the sudden death of a 57-year-old man after he had been handcuffed by Toronto police officers on Sunday night.

According to an SIU statement, officers were called to an apartment building near Sherbourne St. and Dundas St. E. at around 9:30 p.m. on Sunday to deal with a “disturbance call.”

Toronto Police Const. Craig Brister said security guards at the building had taken someone into custody. He wasn’t able to comment further because of the SIU’s investigation.

Police officers arrived at the building’s security office to find the 57-year-old man sitting in a chair, handcuffed. The SIU statement said the man was searched and then sat back down in the chair.

But a short, unspecified time later, the 57-year-old “fell to the ground” and lost all vital signs. Paramedics waiting at the scene performed CPR on the man and took him to hospital, the SIU statement said.

He died at around 11:15 p.m. that night.