Supporters of Rep. Maxine Waters, D-Calif., who gathered outside of her office in Los Angeles on Thursday burned an American flag that they snatched from the back of a pickup truck.

According to the Associated Press, the group had gathered with the expectation they would be confronting a far-right group, called the Oath Keepers, after they said they would hold a rally.

When a vehicle driven by two white men approached, the counter-protesters, who had been chanting "black power" and other slogans, stopped it, opened the doors, and grabbed the flag out of the back.

The truck drove off, but the flag was stepped on and burned. One person yelled, “This is not the American flag, this is their flag," according to the AP, which posted photos of the incident.

[Opinion: Maxine Waters is becoming less keen on the idea of mobs publicly confronting political opponents]

No injuries or arrests have been reported and Waters' office did not immediately reply to the AP's request for comment.

The incident occurred shortly after Waters warned her supporters not to confront a group of armed protesters that were expected to demonstrate outside of her Los Angeles office.

“I have been notified that the Oath Keepers, an antigovernment militia that has staged armed protests in cities across the country, is planning to protest my district office in Los Angeles tomorrow afternoon,” Waters said in a statement Wednesday.

Waters says the Oath Keepers are known for engaging in violent behavior, and she warned her supporters not to be “baited” into confronting them.

The Oath Keepers describe themselves as a “non-partisan association of current and formerly serving military, police, and first responders who pledge to fulfill the oath all military and police take to 'defend the Constitution against all enemies, foreign and domestic.'”

Waters is one of the Democratic politicians who has called for the abolition of U.S. Immigration and Customs Enforcement in response to President Trump's "zero tolerance policy on illegal immigration. She also recently called for people to continue confronting Trump administration officials in public spaces to let them know they are "not welcome anymore, anywhere."

Katelyn Caralle contributed to this report.