The Philadelphia Police Department is investigating an incident captured on a cellphone video in which a white officer is seen mocking and insulting a Black pedestrian and shining a flashlight in his eyes while calling him “boy” and “homie.”

The Police Department took to Twitter on Tuesday to announce that decision and to explain that an Internal Affairs investigation is underway.

“We understand the video circulating has caused anger and disappointment,” the department said in a tweet. “All PPD officers are expected to discharge their duties with honor and integrity.”

The officer, Robert Hoover, could not be reached for comment Tuesday.

The Fraternal Order of Police, Lodge No. 5, the union that represents the city’s 6,000 police officers, “has no comment,” said spokesperson Mike Neilon.

Efforts to reach the man who recorded the video were unsuccessful. It was apparently taken by a man the narrator calls Gabriel, who starts filming Hoover as the officer follows him after he leaves his aunt’s house in the Poplar neighborhood.

The video was first posted on YouTube on Oct. 2 by LackLuster, a channel used to expose police misconduct.

The video begins with Hoover approaching the man with a cellphone in one hand and a flashlight in the other. Hoover, in an animated voice, accuses the man of “chasing” him around. “I got my camera, too. We’ll take selfies,” the officer says. “Come on, homie. Look at me and my homie right here.”

“I’m not your homie, sir,” the man replies before asking Hoover to back up if he is not accusing him of committing a crime.

“You’re not committing a crime. Who said you’re committing a crime?” responds Hoover, who does not back up.

When the man tells Hoover he is in the area because he lives there, the officer laughs and says: “You don’t live down here. Shut your mouth, boy. You don’t live down here. Where you from? Where you from? Cause you ain’t from down here.”

When the man asks for a “white shirt,” a common reference to a department supervisor, Hoover says, “A white shirt! That sounds racist.”

The man insists that Hoover call a sergeant, and the officer retorts, “Call what sergeant? A white sergeant?”

At one point, Hoover tells him, “You’re literally too stupid to insult.” Later, the man repeatedly calls the officer a dummy. Just before the video ends, Hoover can be heard asking, “Why are you following me the f— around?” and ordering the man to put his hands behind his back and to stop resisting.

“I’m not resisting,” he says.

The LackLuster narrator says the man was charged with disorderly conduct and possession of a small amount of marijuana.

“The actions of Officer Hoover are unbecoming of an officer and a disgrace to his department,” the narrator says. “Most would agree that they wouldn’t want to be treated this way, and that no public official should be allowed to act in such a disrespectful manner, especially unprovoked.”

The video elicited outrage and condemnation from social media posters.

“We are watching from Frankfurt, Germany and ask Philadelphia to make sure the police officers conduct themselves with dignity and honor,” Max Ipaduser wrote on YouTube. “Right now we feel shame and disgust at being a sister city to Philadelphia.”