The group responsible for much of the vandalism, arson and violence during Donald Trump’s inauguration is a small corps of anarchists known as the “Black Bloc”.

Police estimated their numbers in the low-100s but accuse them of causing hundreds of thousands of dollars in damage during protests Friday.

The “Black Bloc” makes no secret of its existence, and an umbrella organization called #DisruptJ20 announced well in advance of inauguration day on its social media accounts that un-permitted protests would occur and advised protestors on legal rights.

Black Bloc members organize themselves using social media. Court records show that people charged with felony rioting came from 24 states. Sixty percent of those arrested were from the D.C. region.

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One of the first marches to depart a permitted anti-Trump protest sight at McPherson Square Friday was led by a vanguard of Black Bloc members. They carried banners with anarchist symbols and chanted “No cops, no borders, fight law and order.”

The organization included supporters who were designated as medics to assist protestors hit by police pepper spray or injured in clashes. Police said the group was well prepared ahead of the march with hammers, crowbars, long poles and flares to use in vandalism attacks on buildings and confrontations with police.

Police monitored the Black Bloc’s movements up 14th Street but took no action to stop the march until incidents of vandalism began to occur near Franklin Park. Protesters in black hoods and face masks attacked symbols of corporate culture and wealth.

Among the first targets for window smashing were a Bank of America, a Starbucks, a limousine and a vehicle used by a news crew. Protesters would return to the limousine later in the day and set it on fire.

Many arrest occurred during a seven-hour standoff with police at the intersection of 12th and L NW. where police surrounded a group of protestors in the wake of the early incidents of vandalism.

Police used pepper spray against some who defied police orders to maintain their distance from police lines.

In later encounters on K St. NW near Franklin Park, police threw non-lethal stun grenades and used pepper spray as they advanced on black clad protestors after the protestors threw rocks at police, vandalized news boxes and set small fires. Police also advanced aggressively to make space for firefighters called in to handle the fires.

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The anarchists say their chief enemies are authoritarianism and fascism. They accuse President Donald Trump of both.

Anarchists operate their own media channels and social media accounts and make no secret of their activities.

Supporters are now using social media to organize a legal defense fund for protestors arrested during the inauguration. Most were charged with felony rioting and face up to 10-years in prison.

The modern history of the Black Bloc extends to clashes with police during a 1999 World Trade Organization summit in Seattle. The Black Bloc is active throughout Europe, North America and South America.

In the first 100 days of the Trump administration police are prepared for spontaneous actions by Black Bloc and other protest groups. However, the groups have made no announcements of any planned actions.