NEW YORK (CBSNewYork) -- At least three dozen people were arrested Thursday night as a crowd marched through Manhattan with signs and messages of frustration, after two police shootings that left African-American men dead this week.
The protests were peaceful at first, but arrests followed soon afterward. Cellphone video showed several people in handcuffs after clashes with police.
As WCBS 880's Peter Haskell reported, about 1,000 demonstrators first gathered at Union Square, saying, "Enough is enough." They said too many black men have been killed by police, and while the most recent cases in Minnesota and Louisiana are different, there is a link.
"The fact that they're in the same situation – sitting in a car, standing outside, the same thing happened – people got shot by the police," one protester said. "They weren't presenting a danger to them."
"I think everyone is sick of talking about it, everyone wants to do something about it, and no one really knows what to do right now except to come together and protest," Lisa Bacon of Harlem told CBS2's Tracee Carrasco.
"Feelings of anxiety, feelings of fear, feelings of discomfort, feelings of shame and just overall outcry," said Jean Robeson of Brooklyn.
Protesters marched from Union Square west across 14th Street. They turned on Fifth Avenue and headed north amid one-way southbound traffic, and then turned to Herald Square and headed west.
Some protesters then proceeded north to Times Square, where many were standing in the street as of 9 p.m.
Others continued to march north along Fifth Avenue as far north as 96th Street.
The people who were arrested will face various charges, including obstruction and disorderly conduct, police told CBS2.
The U.S. Department of Justice said Thursday that it will monitor a state investigation in Minnesota in the aftermath of the police shooting that killed Philando Castile. The aftermath of the shooting was streamed live on Facebook.
Diamond Reynolds started recording moments after police officers shot Castile, her boyfriend, during a traffic stop in Falcon Heights on Wednesday.
The death struck a nerve with Mayor Bill de Blasio.
"No parent of color or parent of a child of color in this country can watch that and not be afraid. You fear for the life of a child when you see a situation like this," he said.
Meanwhile, two officers were also placed on administrative leave in Baton Rouge, Louisiana after cell phone video captured the moment 37-year-old Alton Sterling was shot outside of a convenience store.
There were five prior complaints made against the two white officers in that case, the complaints involved the use of force and a vehicle pursuit. That shooting is under investigation by the Department of Justice.
Mayor de Blasio spoke Thursday, about the steps the city is taking to prevent police confrontations from ending in tragedy.
"Just like so many Americans I'm just reeling from having watched these videos," the mayor said.
As CBS2's Tracee Carrasco reported, the mayor was speaking at a news conference about the heat, but couldn't ignore the recent police involved shootings in Louisiana and Minnesota.
"It begs the question -- what kind of training did those officers receive? What were they told about how to do their job? Because it was obviously not the right way," the mayor said, "You look at those two videos, it's very hard to believe that bias was not part of the equation, because of the level of overreaction."
The mayor pointed to the city's decision to re-train all officers on de-escalation approaches -- an effort to avoid a similar situation.
"Focus really on helping them to communicate better with people in the community, it is making a difference, but it is necessary all over the country," he said.
The mayor was confident that it's not only the type of training city cops need, and called for it to be federally mandated.
De Blasio said NYPD officers will be re-trained annually on those practices to avoid improper use of force.
He said the city is also moving aggressively to get body cameras for all officers, but in the heat of the moment does this kind of training really help?
"It matters enormously. If the training isn't given and an untoward circumstance occurs it can be considered negligence," said Robert McCrie of the John Jay College of Criminal Justice.
Experts said each situation is hard to predict.
"In nanoseconds, the police officers have to make decisions. Not easy to do," McCrie said.
The shootings touched de Blasio much deeper, as the father of a bi-racial son his advice to Dante was unwavering.
"As a parent the message we're trying to get across is 'do exactly as the officer says.' But that also has to be a message to our officers to recognize that everyone of these situations is being watched so closely that we want our young people of color to have faith that if they follow the instructions of a police officer they'll come out okay," de Blasio said.
In addition to Manhattan, protests were also held in Newark Thursday evening. People laid in the middle of McCarter Highway near Penn Station, where NJ TRANSIT reported 30-minute bus delays.
Protests were also held in numerous other cities throughout the country.
Hundreds gathered in Washington, D.C. for a rally against police violence, which was held outside the White House.
In St. Paul, Minnesota, an estimated 2,000 protesters were seen outside governor's mansion Thursday night, WCCO-TV, CBS4 Minneapolis reported.
In Chicago, protesters demonstrated outside the Chicago Police Area Central Headquarters on the city's South Side, and then blocked the Dan Ryan Expressway, WBBM-TV, CBS2 Chicago reported.
And in Philadelphia, protesters gathered near the Pennsylvania Convention Center and marched, KYW-TV CBS3 Philadelphia reported.
In Dallas, two police officers were struck when shots were fired from a building during protests Thursday night. Downtown Dallas was ordered cleared out after the protest, KTVT-TV, Dallas reported.
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