Denver police now say officers arrested 18 people during protests near downtown on Tuesday over immigration enforcement.

Dozens of Regional Transportation District routes were detoured or delayed throughout metro Denver on Saturday as thousands of Coloradans gathered for “No Kings” protests.

Eighteen people were arrested Tuesday night after protesters got into confrontations with Denver Police during demonstrations, prompting Mayor Mike Johnston to warn that violent actions could invite the type of federal intervention President Donald Trump has threatened to deploy in cities.

Protesters took to the streets to march against the Trump administration as part of nationwide "No Kings" demonstrations June 14.

The parade, honoring the Army’s long-planned 250th anniversary celebration and coinciding with Trump’s 79th birthday, is set to step off from the Lincoln Memorial under the threat of stormy weather in Washington and protests around the country tied to a turbulent week of immigration enforcement that has involved military deployment in Los Angeles.

Political organizing group Move On, who was a partner in the "No Kings" rallies, echoed the 5 million person estimate in a fundraising email.Start the day smarter. Get all the news you need in your inbox each morning.