NEW YORK (AP) — The New York Police Department was caught off guard by the size of the spring protests after the killing of George Floyd and resorted to aggressive disorder control methods that stoked tensions and stifled free speech, the city's inspector general said in a report released Friday.

The Department of Investigation report followed a six-month probe that focused on the NYPD’s institutional planning and response to the May and June protests after Floyd's killing by police in Minneapolis, rather than on the actions of individual officers.

It criticized tactics that included trapping demonstrators with a technique called kettling, making mass arrests, using pepper spray and batons, and detaining protesters for hours. Too few officers were deployed early in the demonstrations, the report said.

The report also found that Mayor Bill de Blasio's decision to impose a nightly curfew after two days of looting exacerbated conflicts between demonstrators and police officers, who were given mixed messages on how it was to be enforced.

De Blasio's executive order said the curfew applied to everyone, with exceptions for essential workers. In subsequent public statements, he said the curfew wouldn't apply to “peaceful protesters."

The Department of Investigation recommended the NYPD create a unit to lead protest planning and response, adopt policies and training that reinforce respect for First Amendment rights, and improve messaging during demonstrations, such as repeating dispersal orders and staging officers in riot gear out of the view of protesters.

It also recommended that the department no longer use for protests a rapid-response unit that deals in terrorism and other emergencies.

“The problems went beyond poor judgment or misconduct by some individual officers,” Department of Investigation Commissioner Margaret Garnett said at a news conference. “Our investigation found that the NYPD as an institution made a number of key errors or omissions that likely escalated tensions and the potential for violence and certainly contributed to the public perception that the department was suppressing rather than facilitating lawful first amendment assembly and expression.”

Police Commissioner Dermot Shea, who told investigators he objected to the curfew, said in a statement that he intends to incorporate all 20 of the report's recommendations into the department's policies. And de Blasio, in a video response, said the report “makes very clear, we’ve got to do something different and we got to do something better.”

The springtime protests in New York City often featured peaceful daytime rallies and marches that devolved into chaos after dark, as they did in some other cities. Some demonstrators firebombed police cars, vandalized buildings and attacked officers with thrown objects.

Police officers, in turn, at times used what appeared to be arbitrary force, using batons and bicycles wielded like shields to force protesters out of particular areas or break up demonstrations.

Asked at his daily news briefing Friday whether top police officials would be disciplined, de Blasio demurred, saying: “We're definitely going to look at actions of individual commanders down to the precinct level, but I think it's fair to say that what's being pointed out here is not so much time for retribution, honestly, but time for change."

Pat Lynch, the head of the city’s largest police union, said city leaders deserve blame for sending officers out with “no plan, no strategy and no support to deal with unrest that was fundamentally different from any of the thousands of demonstrations that police officers successfully protect every single year.”

“No amount of new training or strategizing will help while politicians continue to undermine police officers and embolden those who create chaos on our streets,” said Lynch, the president of the Police Benevolent Association.

Two other reports in recent months have also criticized the NYPD's handling of the protests.

The civil rights organization Human Rights Watch last month issued a report citing evidence that police planned an aggressive crackdown on protesters on June 4 in the Bronx. The state Attorney General's Office issued a preliminary report in July that cited a “clear breakdown of trust between police and the public."

In October, the New York Civil Liberties Union and the Legal Aid Society sued the city on behalf of protesters who say they were assaulted and abused by police.

“This report confirms that the shocking violence the NYPD employed during the George Floyd protests was directly traceable to the leadership failures of Mayor de Blasio, Police Commissioner Shea and other police leaders who created a de facto policy permitting and encouraging individual officers to target protesters for brutal treatment and unlawful arrests," the NYCLU and Legal Aid Society said in a joint statement.

The Department of Investigation also found that many officers lacked sufficient training on policing protests, and that the department didn’t assess the context or proportion of a potential threat in shaping its protest response.

“Those two weeks in late May and early June were a very painful period in an already deeply challenging year for New York City,” Garnett said. “Our goal was to bring transparency and accountability to the events of that period.”

___

Follow Michael Sisak on Twitter at twitter.com/mikesisak