GUELPH, Ont. -- Ontario's police watchdog is investigating the death of a 49-year-old man in Guelph on Saturday.

The Special Investigations Unit says at about 3 a.m., local police officers responded to a medical call at an apartment building.

They say an unresponsive man was located and police provided medical assistance until emergency services arrived.

The man was pronounced dead at the scene about an hour later.

The SIU has assigned a team of three investigators to the case, and it's urging anyone with information to come forward.

The SIU investigates all reports where there has been death, serious injury or allegations of sexual assault involving police.