The New York Police Department is investigating whether at least one of its members was involved in last week's riot in Washington, D.C., as the Big Apple's mayor warned Monday that any city employee involved in the attack "will be terminated." 

NYPD Commissioner Dermot Shea told Spectrum NY1 that "there is one investigation that is active on one member" in connection with Wednesday’s attack at the U.S. Capitol.

"There is no name yet released because we don't know if it's true or not," Shea said. "But I can tell you that anyone committing crimes certainly would have a very short shelf life with the NYPD."

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Shea, who announced last week he had tested positive for the novel coronavirus, said he had spoken last night with Joseph Resnick, who heads the department’s Internal Affairs Bureau, on the matter.

Speaking about Wednesday's events on Capitol Hill, Shea said he was "deep in COVID" at the time, but added: "Like everyone else, I was disgusted by what I saw."

On Saturday, the Fire Department of New York confirmed in a statement to Fox News that the agency "received anonymous allegations that active or retired members were present at the events at the United States Capitol on January 6," said Frank Dwyer, FDNY's deputy commissioner of public information and external affairs. The department provided the FBI with the information. 

A source familiar with the matter told Fox News on Monday the FDNY received two tips from two individuals linking them to the Capitol Hill events. The source could not speak to whether they were active duty or retired members, and said the tips "generically stated that they were at the events at the Capitol."

Also on Monday, Mayor Bill de Blasio issued a scathing rebuke on any city employees who participated in the violent events, saying they'd be out of a job if caught. 

"Any New York City employee, any part of the city government, who participated in an attack on our democratic institutions, who participated in an insurrection at the Capitol, will be terminated. Period," the Democratic mayor told reporters. "If we have proof that someone violently attacked our United States government, they will not be working for New York City any longer."

Last week, hundreds of people - some armed with guns - pushed their way into the halls of the U.S. Capitol, smashed or dismantled property and went into House and Senate leaders’ chambers. Meanwhile, Hill staffers and lawmakers were under lockdown, or hid behind chairs or under desks and tables.

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Five people, including a U.S. Capitol Police officer, died during or in connection with Wednesday's events. 

As of Monday morning, the FBI told Fox News it had received "over 40,000 digital media tips, including video and photos, from the public."

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Shea added Monday that law enforcement officials in Washington, D.C. asked the NYPD one-to-two months ago if the department would send members to the capital for the inauguration.

"We complied and said we would be happy to," he said. "I think it’s more important than ever to show the solidarity with law enforcement, with the country as a whole, that what that building stands for – what our freedom stands for – is something that we should never take for granted and has to stand tall above all else."

Fox News' Caitlin McFall contributed to this report.