Police identified him as 25-year-old Quran Campbell. The second suspect, Banks Shaborn, also 25, was being held on $10,000 bail.
A senior police official called these developments "stunning."
"Quran Campbell is captured on video for the nation to witness him viciously assault 3 cops in uniform - 1 who lost consciousness. Judge Robert Rosenthal's reckless decision to release Mr. Campbell WITHOUT BAIL endangers every NYer and the officers who risk it all to protect them," Monahan posted Friday morning on Twitter. "My thanks to the @ManhattanDA's Office for recognizing the seriousness and strength of this case by requesting $75,000 bail."
The attack happened on Wednesday, during what was supposed to be a peaceful protest on the Brooklyn Bridge.
Eight officers were injured during the protest.
The NYPD also arrested a woman seen dressed in red who allegedly ran up to officers who were in the middle of an arrest and started swinging a cane at them, causing injuries. Chief of Department Monahan was among the eight officers injured.
Woman arrested for allegedly attacking NYPD officers during protest
Chanice Reyes, 24, is accused of assaulting a lieutenant on the Brooklyn Bridge. She was taken to Bellevue Hospital for a psychological evaluation.
On Wednesday, police intended to keep two groups of protesters separate, but when pro-police marchers got to the Manhattan side of the Brooklyn Bridge, they met up with anti-police protesters occupying City Hall and chaos broke out around 10 a.m.
NewsCopter 7 was next to City Hall where those marchers stopped to hold a peaceful rally.
Raw Video: NewsCopter 7 over City Hall protesters
Protesters at the "Defund the Police" encampment clashed with police and at least eight NYPD officers suffered injuries -- Monahan suffered a hand injury, a lieutenant was struck in the head, a sergeant was struck in the head and a lieutenant suffered an eye socket fracture. The other officers suffered minor injuries.
NYPD officers hurt, protesters arrested in clashes near NYC City Hall
"They literally arrested about 20 of our folks, as this protest, stop, we're going to arrest Black Lives Matter protesters and then allow this protest to peacefully come by," said Jonathan Lykes, Black Youth Project 100. "They didn't want a counter protest, they didn't want democracy, they didn't want freedom in this moment."
Police say 36 people were arrested, including individuals who assaulted cops.
"These are the conditions your officers have to operate in every day while they continue to protect your neighborhoods," said NYPD Commissioner Dermot Shea. "Such assaults are ALWAYS unacceptable, and should outrage us all."
NYPD Sergeants' Union President Ed Mullins said Mayor Bill de Blasio has lost control of the city.
"This guy in City Hall will not let us do our job," Mullins said. "It's time that stops, and it's time they have a voice."
Mullins was among the organizers of the march, along with ministers from Brooklyn.
De Blasio made a show of signing some police reform measures, including a ban on chokeholds, but some say it's time the mayor shows support for the police.
Dozens arrested after multiple NYPD officers hurt in clash with protesters
Anti-police activists, camped in City Hall Park, insisted it was a provocation that led to the melee.
"They didn't want a counter-protest," anti-police activist Jonathan Lykes said. "They didn't want democracy, they didn't want freedom in this moment. They set us up, intentionally."
But supporters of the police say concessions to the activists have gone too far.
"The police are here to help us, you know, not to hurt us," pro-police demonstrator Clyde Jasmin said. "Report these shootings and murders and hopefully get our city back."
RELATED: In moving show of support, one of NYC's top cops takes a knee, hugs George Floyd protesters
"We're fighting for unity. It just seems that there's so much violence," said Bill Casey, Retired Sergeant Association. "And the cops are being portrayed as villains instead of what they really are, which is heroes."
"We support the police and we need their help because this city is becoming a war zone," said Tamara Lashchyk, a pro-police demonstrator.
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