Police are looking into a viral video that appears to show a group of teenage boys engage in a mugging spree, knocking people off of their bicycles in Minneapolis and St. Paul.

The video shows the boys smiling as they attack a man on a bike, a jogger and even some other young kids.

The "stars" of the video, which was posted on YouTube but was subsequently removed some time Tuesday afternoon, make no attempt to hide their identities. They are shown smiling at the camera before ambushing their victims. One of them dons a mask depicting Heath Ledger's Joker from "The Dark Knight."

The video attracted a lot of attention on the Internet, with links passed around on message boards and social networking sites.

It also attracted the attention of police in Minneapolis and St. Paul, who aren't yet convinced of the video's veracity but are taking it seriously nonetheless, reports CBS station WCCO-TV in Minneapolis.

St. Paul Police Sgt. Paul Schnell said Tuesday afternoon that they had identified several of the people in the video and were going to interview at least one person Tuesday afternoon. Schnell said they believe the video was shot sometime last weekend.

He said the main message is, this needs to stop.

"I hope these things are staged, but they are very concerning," said Minneapolis Police Chief Tim Dolan, adding that police are asking any victims to come forward if they were attacked by the boys in the video.

Investigators in both Minneapolis and St. Paul are studying the video to identify possible locations. At least one of the shots in the video appears to have been shot by the Recreation Center in Crocus Hill neighborhood in St. Paul.

Investigators are also looking into whether any crime reports match up with locations depicted in the video.