A video of a confrontation between a Colorado Rockies fan and a Denver police officer has gone viral and led to an internal investigation at the Denver Police Department.

In the video, first posted Wednesday on Facebook, Denver police Capt. Joe Black shoves 22-year-old Alex Buck three times before dropping him to his knees and placing him in handcuffs.

The video does not capture what led to the confrontation at Tuesday night’s game versus the Washington Nationals but picks up the incident as Black is ordering the fan to answer a question. It appears to have been filmed on a concourse inside Coors Field.

Black tells the fan to sit down three times before shoving him.

“Officer, that is abuse,” Buck says as he bounces back to his feet.

Black then shoves Buck two more times.

Commander Matt Murray, the department’s chief of staff, declined to release details of the incident, including what led to the confrontation and whether the man was charged with any crime.

“We’re investigating and that’s it,” Murray said.

On Thursday night, the police department sent out three tweets assuring the community that the incident was being taken seriously.

“COMMUNITY: We want everyone to know that Chief (Robert) White “hears” your concern about the recent video involving DPD. He is closely monitoring the investigation and will share the results with everyone when appropriate,” department officials said in the tweets. “If the investigation results in a violation, then the officer will be held accountable. Thank you for your patience and understanding as we investigate.”

Jay Alves, the Rockies vice president of communications, referred questions about the incident to Denver police.

VIDEO: See the Facebook video of the Coors Field confrontation.

Black, who commands the department’s juvenile division, was working off-duty security during the baseball game, Murray said.

In the video, Buck tells the officer he is 22-years-old and had three beers. He also repeatedly yells that the officer is violating the rights of an “American citizen.”

At one point, Buck tells the officer, “Abuse me again. As a citizen of the United States of American, abuse me again.”

Friends of Buck, who are not seen on camera, are heard telling him to quit talking before he causes himself more trouble.

Buck told The Denver Post via a Facebook message that he had not been arrested or charged after the incident. He said he was ejected from the ball park.

The video had been shared nearly 30,000 times by shortly after 9 p.m. Thursday. Murray said people have been posting links to it on the department’s Facebook page.

Denver police have contacted Buck as part of the investigation, Murray said.

“We care about this,” he said. “We’re going to do the right thing.”

Noelle Phillips: 303-954-1661, nphillips@denverpost.com or twitter.com/Noelle_Phillips