Justin Bieber Investigated for Nerf Gun Assault >>Hollywood

This really is not Justin Bieber's week.

First, the singer was accused of cheating on Selena Gomez while smoking pot in December with someone named Mimi Jenson.

Then, a radio host in Charlotte said Bieber was really mean to her at the gym.

Now, Canadian cops are actually investigating a complaint by a woman who was in the vicinity of Bieber backstage at a November concert in Ottawa.

TMZ sources say Bieber was horsing around with his very young brother and sister when one of his Nerf darts hit this bystander.

She proceeded to flip out and file a police report over the incident.

For whatever reason, the Canadian mounties are taking this report seriously enough to confer with witnesses an