Brooklyn Park Police Chief Mark Bruley said that it was not a police officer.

According to this article: https://www.fox9.com/news/melissa-hortman-john-hoffman-lawmakers-shot-minnesota

Police say they are looking for a suspect in multiple targeted shootings. The suspect is armed and dangerous. The suspect is a white man with brown hair wearing black body armor over a blue shirt and blue pants, and he may be impersonating law enforcement.

It’s the outfit that he is wearing (black body armor over a blue shirt and blue pants) that may give the appearance of law enforcement.

This image is from https://www.postbulletin.com/news/minnesota/police-officer-killed-in-minneapolis-shooting-remembered-for-heroism

The victims:

Hortman, was Democrat from Brooklyn Park, and represented District 34B. Hoffman, a Democrat from Champlin, represents Senate District 34.