So far, two officers have been suspended and a third was placed on modified duty. A precinct commander has also been transferred.
"I took action the last couple weeks in suspending a number of officers," Shea said during an internal pep talk he hosted on Twitter. "There will probably be more."
Police actions during the protests will come under review by the New York Attorney General's Office, and former United States Attorney General Loretta Lynch has been brought on as an adviser.
Internally, Shea said, he does not want bad actors to "stain" the profession.
"We cannot have people acting inappropriately," he said. "I know the difficult circumstances you are under, I know there are some people who don't understand law enforcement recommending things that are completely impractical. I get it. I know. But right is right and wrong is wrong."
While Shea said it would "fair" for police officers to think the city is "lined up against you," he sought to reassure the rank and file they have public support even as the death of George Floyd has caused nationwide introspection about police treatment of black people.
"You turn on the TV and you will hear reform, reform, reform," Shea said. "Nobody is mentioning that we have been reforming for six years. The policies and practices that we've put in place are many of the reforms that are being recommended today."
Chief of Department Terry Monahan also sought to reassure officers, saying in a videotaped message to "tired," "stressed out," "under-appreciated" New York City police officers the the department pledged to explain and defend their actions during protests and unrest of the last two weeks.
"You did a fantastic job," Monahan said in the video obtained by ABC News. "There are critics, many armchair critics, who sat on their couch and watched clips on TV who look at the job you did and say you didn't do something right."
Monahan, the NYPD's highest-ranking uniformed officer, conceded the department was not perfect but said he would make sure the New York Attorney General's Office, the Department of Investigation, and district attorney's offices understand the context of officer actions.
"The attacks on our police officers, the stresses that you were under each and every day to bring order to the streets, I know what it is," he said. "And I will make sure whoever is doing an investigation understands what was going on on those streets."
The death of Eric Garner on Staten Island prompted the NYPD to adopt body cameras and de-escalation training. This week, First Deputy Commissioner Ben Tucker told City Council the department could support a ban on chokeholds.
"The department can support this legislation with minor amendments," Tucker said.
New York City Mayor Bill de Blasio and Governor Andrew Cuomo have been vowing to be agents of change in leading police reforms.
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