WASHINGTON (AP) — Police in the nation's capital are asking for public assistance in identifying people responsible for burning Black Lives Matter banners and damaging local churches during weekend clashes between local activists and supporters of President Donald Trump.

The Metropolitan Police Department released several photos of the alleged perpetrators Monday and are offering up to $1,000 reward for information leading to an arrest, with the FBI's Washington field office offering an addition $2,000 reward.

Police Chief Peter Newsham said four local churches were damaged. In some cases a Black Lives Matter banner was torn down and set ablaze. The photos of the perpetrators all show different bearded white men, all wearing the distinctive black and yellow of the Proud Boys, a neo-fascist group known to incite street violence.

A large contingent of Proud Boys from different states flooded into the capital over the weekend to participate in rallies supporting outgoing President Donald Trump's unproven claims that he lost the presidential election due to widespread voter fraud.

After dark, large groups of Proud Boys roamed the downtown streets and confronted a group of local activists, including antifa, who sought to protect the space around Black Lives Matter Plaza. Four people were stabbed in the clashes and 33 people were arrested, with charges ranging from simple assault and assault on a police officer to disorderly conduct.

Newsham said the church vandalism incidents were being investigated as hate crimes.

“Whenever anyone attacks our places of worship, I think it's unsettling for all of us,” he said.

Mayor Muriel Bowser called the incident “disgusting and vile” and blamed the violence on “people who came to our city intent on violence against others.”

The local Black Lives Matter affiliate has accused the MPD of allowing the Proud Boys to run rampant downtown.

Nee Nee Taylor, a core organizer with Black Lives Matter DC, charged the MPD with “protecting white supremacists” and said dozens of local activists were arrested “just for being Black and trying to defend themselves.”

Newsham denied those charges, saying his officers were trying to keep the peace in a chaotic atmosphere with “mutual combatants” on the scene.

“We were just trying to stay between the groups,” he said. “It's unfortunate if somebody feels like somebody was being treated differently.”