Practical jokers have delighted for years in tormenting celebrities at home by calling in bogus reports of violence and provoking huge police responses.

Now they have found a way to turn their pranks into an instant public spectacle by setting their sights on a new set of victims: video gamers who play live on the Internet, often in front of huge online audiences.

Last month, several hundred people were watching Joshua Peters as he played the game RuneScape from his parents’ home in St. Cloud, Minn. A video of Mr. Peters shows him suddenly leaving his computer when police officers appear at the house and order him and his family at gunpoint to lie face down on the ground, the New York Times reports.

Someone had called 911 claiming Mr. Peters had just shot his roommate. Shortly after defusing the situation, Mr. Peters returned to his live stream and tearfully rebuked the culprit, whom he assumed was among his audience. Mr. Peters, 27, said 20 to 30 people on the Internet immediately claimed responsibility for the hoax, but he has no idea why they picked on him.