Justin Bieber is reportedly being investigated for assault -- with a Nerf gun. According to TMZ, during Justin's Ottawa, Canada tour stop Justin was Nerf fighting with his 3-year-old brother and 4-year-old sister when apparently one of the darts hit a female employee of the venue. The woman reportedly got upset and told Bieber's people she was a security guard for the venue. She reportedly filed a police report and the cops are reportedly taking it seriously -- and have actually interviewed some people at the venue. However, Bieber is trying to settle fans concerns of him turning into a total bad boy. Justin reportedly tweeted, "some of the rumors about me are just so ridiculous u gotta laugh. people are creative. kinda over it. im a good guy. that's all."