Demonstrators flash the peace sign during an anti-NATO protest march in Chicago May 20, 2012. Four police officers were injured and 45 demonstrators arrested after baton-wielding police clashed with anti-war protesters marching on the NATO summit in Chicago on Sunday, police said. Reuters/Eric Thayer

Check back for updates. This is an early report.

NATO has been a weird mix of two normally separate and entirely autonomous events: permitted marches, run usually by unions, and the black bloc’s runs, which are complete anarchy by anarchists who lead police on wild goose chases through the city.

First there was the event organized by National Nurses United at Daley Plaza, an entirely peaceful demonstration of around a thousand individuals, including rocker Tom Morello, who demanded the US government start properly funding health and stop funding death with an ever-expanding military budget. Also, the nurses were pushing the Robin Hood tax, a small trading tax on Wall Street that would raise badly needed revenue.

Contrast the totally adorable image of middle-aged nurses dancing around to James Brown in their red NNU shirts and Robin Hood green masks and hats with the chaos of the black bloc run Saturday night. Contrary to the stereotypical image of the property damaging anarchists presented by the media, this group appeared satisfied to merely race around the city, leading the Chicago police on an unending parade.

It was the police who first escalated the violence by clubbing protesters across their heads with billy clubs, roughly arresting activists, and acting extremely aggressively toward media. For example, shoving press back towards the sidewalk as they attempted to photograph arrests, whilst shouting “Back the fuck up!”

Several individuals were arrested Saturday in a brutal fashion that settled the brief debate over if the CPD would be a warmer, friendlier version of the NYPD, which adopted a legendarily aggressive management style with Occupy Wall Street.

Much praise has been heaped upon the CPD for their ginger approach toward policing protesters. However, while the CPD might have initially lacked the bash-you-in-the-face forthrightness of the NYPD, that doesn’t mean there isn’t some seriously creepy stuff happening behind the scenes.

To select just one story: In the early hours of Sunday, livestreamers Tim Pool and Luke Rudkowski were pulled over by the CPD, and had their vehicle surrounded by police, who drew their weapons upon the activists.

Later, police said Pool and Rudkowski’s vehicle matched the description of another vehicle they sought.

Saturday was Chicago’s first taste of police brutality, and the weird duality of the marches continued into the next day when veterans and thousands of protesters peacefully marched to NATO, or as close as they could get to the conference, anyway, in order for the vets to return their service medals.

The black bloc was present then, too—actually leading the march at times—but all was peaceful until after the veterans returned their medals in a highly dramatic, and at times, extremely moving fashion. Since the way into the NATO conference itself was blocked, veterans threw their medals in the general direction of McCormick Place.

One emotional veteran addressed the crowd, “Looking out at this peace-loving crowd, I’m convinced my daughters will have peace.”

Veteran Scott Olsen, perhaps best known for being severely injured by police during an Occupy Oakland march, returned his service medals, as well.

“These medals once made me feel good,” said Olsen, adding, “I came back to reality. I don’t like these anymore.”

It was after the veterans spoke to the crowd that police ramped up their official policy of unbridled aggression. The veterans climbed down from the stage and dispersed, leaving the remaining crowd to mill about as they tried to figure out what to do next.

Initially, no order for dispersal was given, when suddenly police arrived in what can only be described as souped-up riot gear that gave the officers the appearance of Storm Troopers.

CPD appeared ready for a violent confrontation with protesters, which of course became a self-fulfilling prophecy. Police attacked protesters, clubbing them across their heads with billy clubs, and generally shoving activists around.

At least two protesters were badly injured.

“Just saw protesters gushing blood from head,” independent journalist John Knefel tweeted, “Photog witnessed it, called it terrifying.”

Later, Knefel tweeted, “2 protesters bleeding from head being treated by medics in alley.”

The infamous LRAD, or sound cannon, also made an appearance. Additionally, independent journalist Jesse Myerson tweeted that he saw Chicago police dolling out ear plugs among themselves, and protesters tweeted they too were suiting up with earplugs and gas masks after several witnesses noticed police and firefighters donning masks.

(This story is still developing. Check back for updates.)