Ontario's Special Investigation Unit has been called in to investigate after a man fell from an apartment balcony in downtown Toronto overnight.

Police confirm the call came in shortly before midnight on Tuesday for police to attend an apartment at 20 Vanauley Walk, near Queen and Spadina Streets.

Emergency Medical Services say paramedics arrived to find a man injured in a fall from a third- or fifth-storey balcony.

The man was conscious but in serious condition when he was taken to St. Michael's Hospital.

Reports suggest police were attempting to detain the man at the time of the fall.

The SIU is an arm's length agency that investigates reports involving police that involve death, serious injury or allegations of sexual assault.