TORONTO -- Ontario's police watchdog says criminal charges weren't warranted against an officer whose actions led a man to lose hearing in his left ear.

The Special Investigations Unit says the incident happened while officers with Halton regional police were executing a search warrant at a home in Milton, Ont., in January 2017.

The agency says the officer under investigation deployed a "distractionary device" beside the homeowner, causing the man's ear drum to rupture.

It says the device also burned off the hair on his left forearm.

In the SIU decision, director Tony Loparco writes that the incident occurred in the dark, and the officer was carrying out a plan laid out ahead of time.

He says he was able to infer that when the officer deployed the distractionary device, he did not know that the homeowner was beside him.