British Columbia's police watchdog is investigating the death of a man who was pepper sprayed and shocked with a stun gun by Mounties on Sunday.

RCMP said the incident happened in Whistler at about 11 a.m. PT, after people called to report an intoxicated man causing a disturbance at a local business.

The Independent Investigations Office of B.C. (IIO) has since confirmed the man was inside Stonesedge Kitchen in the Whistler Village. The restaurant was open at the time.

"We do understand there were many witnesses," said Ron MacDonald, chief civilian director of the IIO.

A statement from RCMP said several officers used pepper spray on the man, stunned him with a conducted energy weapon and used their batons "in an effort to gain control of him."

During the interaction, they said, the man "suddenly became still" and officers began CPR as they called paramedics.

He died after being taken to hospital.

RCMP said three officers were treated in hospital for minor injuries.

MacDonald, speaking for the IIO, said the man was in his late 40s and "worked in the area."

The director said investigators are looking for witnesses to come forward.

"We have spoken with some witnesses, but we hope to hear from anyone and everyone who may have any evidence to offer from what they either saw or heard during this event," MacDonald said.

Those with information are asked to call the IIO witness line at 1-855-446-8477.