Ontario's Special Investigations Unit is investigating the death of a man who died after being arrested at a Toronto grocery store.

According to the SIU, the man was apprehended by security staff at a No Frills grocery store at Lawrence Avenue and Markham Road on Sunday morning.

The man went into medical distress after being taken into custody by a Toronto police officer. He was transported to Scarborough General Hospital by ambulance, where he was pronounced dead.

A post mortem was scheduled for Monday.