You can file a Code of Conduct incident report using this Google Form. This will share your report with the CoC committee, and they will contact you promptly.
If you do not feel comfortable using the form, you can contact anyone on the CoC committee directly, using the email addresses shared in the Enforcement manual. You can do this if the incident involves someone on the CoC committee.
If you believe someone is in physical danger, please contact the appropriate emergency responders.