How do you report dangerous dogs?

I witnessed a close call on my way to work this morning.

First I tried calling the area police station to report it, they referred me to the Regional Corporation. The Regional Corporation referred me to their health department at a different phone number. I spoke to Risha there who said they do not have a dog catching unit but she will take the report. I gave her the location and other details she asked including my name and phone number. She said a supervisor would investigate the complaint.