Officers in riot gear used pepper spray on several demonstrators who took to the streets of downtown Denver in protest of police violence and the Albuquerque police shootings.
At least six people were arrested in Saturday evening's protest and march by the group, called Anonymous.
"Police did use pepper spray to stop people who were attempting to interfere with and stop on-going arrests," Denver police tweeted.
Some of the protesters tell 7NEWS police descended on them nearly 10 minutes after the demonstration started.
Witnesses reported officers in riot gear following marchers as they made their way through the streets and the protesters dispersed.