Police in Littleton in August investigate reports of a shooting at an office building in the 1200 block of W. Mineral that turned out to be a case of "swatting." (credit: Alison Betts)

DENVER (AP/CBS4) — The calls to 911 raised an instant alarm: One caller said he shot his co-workers at a Colorado video game company and had hostages. Another in Florida said her father was drunk, wielding a machine gun and threatening their family.

A third caller on New York’s Long Island claimed to have killed his mother and threatened to shoot first responders.

In each case, SWAT teams dispatched to the scene found no violent criminals or wounded victims — only video game players sitting at their computers, the startled victims of a hoax known as “swatting.”

Authorities say the hoax that initially targeted celebrities has now become a way for players of combat-themed video games to retaliate against opponents while thousands of spectators watch. The perpetrators can watch their hijinks unfold minute by minute in a window that shows a live video image of other players.

“It’s like creating your own episode of ‘Cops,'” said Dr. John Grohol, a research psychologist who studies online behavior, referring to the long-running reality TV show that follows officers on patrol.

The players, who are often many miles away, look up their opponent’s addresses in phone directories, sometimes using services that can find unlisted numbers. They also exploit online programs that trick 911 dispatchers into believing an emergency call is coming from the victim’s phone or address. All the while, they conceal their own identities and locations.

Authorities spent an estimated $100,000 to send more than 60 officers in April to the hoax in Long Beach, New York. Investigators said the caller was upset over losing a game of Call of Duty when he called police using Skype. SWAT officers found only a teenager wearing headphones.

In Bradenton, Florida, at least 15 officers showed up at the home of a professional video game player on Aug. 31 after a caller posing as his young daughter phoned in a report that he was armed and drunk. Instead, they found him playing Minecraft for a live audience over Twitch.tv, an online network with millions of viewers.

“The officers responding do not know, other than the information they’re getting over the radio, exactly what is going on,” said Bradenton police Capt. William Fowler.

Less than a week later, police received another bogus call routed through the man’s phone that made it appear he had called in a bomb threat to a Bradenton gas station.

A Connecticut man was arrested Sept. 10 on federal charges that he made swatting calls there and in at least four other states. Authorities say Matthew Tollis, 21, belonged to a group that referred to itself as TeAM Crucifix or Die. Other members live in the United Kingdom, according to the FBI, which is still trying to learn their identities.

Swatting captured headlines several years ago, when a series of celebrity homes were targeted in Los Angeles. Police were so concerned about copycat crimes that they stopped releasing any public information when a hoax occurred. Officers made at least one arrest, a juvenile who targeted Justin Bieber and Ashton Kutcher.

“You can literally do it from around the world,” said Justin Cappos, assistant professor of computer science at New York University. “It can be very challenging (to solve) depending on the sophistication of the person doing it.”

Realizing the difficulty, police in Littleton sought help from FBI agents in Denver who are specially trained to solve cyber-crime.

RELATED: ‘I Think We’re Getting Swatted’: Employee’s Reaction During False Shooting Report

Grohol, the psychologist, said the prevalence of live game-streaming might be one reason for the trend. As the victim in the Colorado case, Jordan Mathewson, put it to a Denver TV station: “They get to see all this go down right before their eyes and, you know, it’s fun to them.”

Intensely competitive war games that blur the lines of fantasy and reality could also contribute, said Dr. Kimberly Young, a psychologist who directs the Center for Internet Addiction Recovery in Bradford, Pennsylvania.

“They want to win at all costs, including jeopardizing someone’s safety,” she said. “Real life becomes almost meaningless because they’re so entrenched and involved in these games. Swatting, to them, seems like part of the game.”

A video of the Aug. 27 incident in Littleton posted on YouTube shows Mathewson playing Call of Duty when he hears officers approaching.

“I think we’re getting swatted,” he says, raising his hands as heavily armed officers shout for him to get on the ground. He drops, and officers handcuff and frisk him.

“That’s live streaming,” Mathewson tells the officers. “I guess a joker thought it would be funny to call you guys in.”

Nobody has been arrested in the Littleton case.

By SADIE GURMAN, Associated Press

(TM and © Copyright 2014 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2014 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)