The F.B.I. and Minnesota law enforcement authorities are investigating the arrest of a black man who died after being handcuffed and pinned to the ground by an officer’s knee, in an episode filmed by a bystander and denounced by the mayor on Tuesday.

The arrest took place on Monday evening, the Minneapolis Police Department said in a statement, after officers responded to a call about a man suspected of forgery. The police said the man, believed to be in his 40s, was found sitting on top of a blue car and “appeared to be under the influence.”

“He was ordered to step from his car,” the department’s statement said. “After he got out, he physically resisted officers. Officers were able to get the suspect into handcuffs and noted he appeared to be suffering medical distress.”

The statement said that officers called for an ambulance and that the man was taken to Hennepin County Medical Center, “where he died a short time later.”

On Tuesday morning, without referring to the video recorded by a bystander, the police updated a statement, titled “Man Dies After Medical Incident During Police Interaction,” that said additional information had “been made available” and that the F.B.I. was joining the investigation.

The bystander video that circulated widely on social media Monday night shows a white Minneapolis police officer pressing his knee into a black man’s neck during an arrest, as the man repeatedly says “I can’t breathe” and “please I can’t breathe.”

Within minutes the man, lying face down in the street with his hands cuffed behind his back, becomes silent and motionless, the video shows; the officer continues to pin the man to the pavement with his knee.

Bystanders plead and curse, begging the officer to stop and telling him the man’s nose is bleeding. Another officer faces the people gathered on the sidewalk. An ambulance medic arrives and, reaching under the officer’s knee, feels for a pulse on the man’s neck.

The medic turns away, and a stretcher is wheeled over. The arrested man is then rolled onto the stretcher, loaded into an ambulance and taken away.

The video did not show what happened before the officer pinned the man to the ground by his neck. Chief Medaria Arradondo of the Minneapolis Police said at a news conference Tuesday that he had received information the night before that he “deemed necessary to contact the special agent in charge of the Minneapolis bureau of the F.B.I.”

He said he asked the agency to investigate, and declined to comment on what information he received.

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The F.B.I. is conducting a federal civil rights investigation, the Minnesota Bureau of Criminal Apprehension said in a statement. The state bureau also said that it was conducting its own investigation at the request of the police department, and that it would release its findings to the Hennepin County district attorney’s office.

The name of the man will be released by the county medical examiner’s office after his family has been notified and the autopsy is completed, it said. The names of the officers would be released after interviews, it added.

Senator Amy Klobuchar, Democrat of Minnesota, called in a statement for a “complete and thorough” investigation into the encounter, which she described as “another horrifying and gut-wrenching instance of an African-American man dying.”

The mayor of Minneapolis, Jacob Frey, on Tuesday described the event as “awful” and “traumatic.”

“Being black in America should not be a death sentence. For five minutes, we watched a white officer press his knee into a black man’s neck. Five minutes,” Mr. Frey said in a statement.

“When you hear someone calling for help, you’re supposed to help. This officer failed in the most basic, human sense,” he said. “All I keep coming back to is this: This man should not have died.”

The police department’s statement said that no weapons were used, and that the officers’ body cameras were recording. Mr. Frey said at a news conference that he had seen the video “taken and posted by a civilian” but not the body camera footage.

“Whatever the investigation reveals, it does not change the simple truth: He should still be with us this morning,” the mayor said. “I believe what I saw and what I saw is wrong on every level.”

F.B.I. to Investigate Arrest of Black Man Who Died After Being Pinned by Officer - The New York Times

The video looks damning. The guy just slowly suffocates while the officer is kneeling on his neck.