The Miami Police Department is conducting an internal investigation after a video showed a police officer punching a suspect during an arrest on Halloween night in Coconut Grove.

The images show a police officer repeatedly punching a suspect, who appeared subdued on the ground, as witnesses yelled "that's on video! That's on video!"

"What you see makes you wonder if the police officer went beyond the call of duty," said Miami Mayor Tomas Regalado after watching the video Wednesday.

When asked if any one had informed him of the incident, he said, "absolutely not. Nobody, and they should have."

Miami police spokesman Delrish Moss said the police chief Miguel A. Exposito had been made aware of the existence of the video. Regalado said he planned to meet with Exposito on Thursday.

"It's an open internal affairs investigation," said Moss.

Stephen Murray, an elected member of the Coconut Grove Village Council, said a friend shared the video with him.

"I was pretty shocked," said Murray. "This reflects poorly on the hundreds of officers who use restraint and serve the city every day."