More than 50 public and private agencies met Monday morning at NYPD headquarters to prepare for the worst ahead of Pope Francis’ visit to New York City next week, which Police Commissioner Bill Bratton says will likely the largest security challenge in the city’s history.

Law enforcement officers and agency officials spent the morning at 1 Police Plaza in a “tabletop exercise” that prepared for two hypothetical active shooters — one at at a hospital and the other at a train station — a power outage and a building collapse on Cliff Street.

“We believe that this event is going to be the largest security challenge the city and this department has ever faced,” Commissioner Bill Bratton said at an afternoon press conference. 

Pope Francis arrives in New York on the afternoon of Thursday, Sept. 24, and is scheduled to say an evening prayer at St. Patrick’s Cathedral. 

On Friday, Sept. 25, Francis will address the UN General Assembly, hold an interfaith service at the 9/11 memorial, visit an East Harlem school, take a motorcade through Central Park and officiate Mass at Madison Square Garden. He leaves for Philadelphia early Saturday, Sept. 26.  

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The pope’s arrival coincides with the 70th United Nations General Assembly — with about 170, or 90 percent, of the world’s leaders set to attend.

Mayor Bill de Blasio, who observed part of the training, said the pope’s “unprecedented visit” will be “fuel for the constant betterment of our city for years and years to come,” and that the NYPD “has been through it all and is ready for it all.”

De Blasio also urged New Yorkers to be patient with the numerous street closures and other changes that are expected next week. 

“Of course, there will be street closures, there will be inconveniences … [but] New Yorkers are tough and resilient, we can handle it .. we know what it is to be a capital of the world,” de Blasio said. 

RELATED: Pope Francis visit only one of many events having the city scrambling in September

The U.S. Secret Service is the leading security agency for the pope's visit. Robert Sica, head of the New York office of the Secret Service, offered little details on the Pope’s travel paths, and what kind of vehicle he will be traveling in. Sica did say the Secret Service is building a security wall for the pontiff’s Central Park visit, and the pope will be traveling as he is accustomed to in Italy and on other international trips.  

Bratton said the NYPD has been working with the archdiocese and papal representatives to balance Pope Francis’ desire to get close to people and safety.

“We are very comfortable that we are going to meet all sets of needs in a very safe [way],” Bratton said. 

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De Blasio, Bratton and other law enforcement officials also toured vehicles that will be used for pope security, and took a look at cameras and explosive and radiation detecting devices. 

Bratton said there is not a final count of officers for the pope’s visit, which is expected to be in the thousands, or the final price tag. 

Information from a pool report from J. David Goodman, New York Times was used in this report.