Members of Congress heard eye-opening testimony Thursday on the danger posed by extremist groups from both ends of the political spectrum.

The subcommittee hearing chaired by Rep. Max Rose (D-NY) looked at the “boogaloo” movement, the slang term is used to refer to a second Civil War or a collapse of civilization.

Experts also looked at the actions of Antifa, the Proud Boys, Anarchists, Oathkeepers and the Three Percenters.

Experts said violence can spread quickly from comments online to action. They said the greatest danger now seems to be from right-wing extremists.

“If we do not gather the courage to act, law enforcement officials, law-abiding citizens will die," Rep. Rose said. "So now when and if that happens, we have no excuse.”

Read more: WPIX 11 (New York)