911

LOGAN -- Northern Utah police are encouraging residents to register their cell phones with area emergency dispatch systems.

A California couple with a 2-year-old daughter is awakened late at night by heavily armed police storming their home after a false report of a shooting.

A Texas family is stunned when officers with automatic weapons respond to their house expecting a drug-fueled murderer who is demanding $50,000 in exchange for hostages.

And a Wyckoff, N.J., neighborhood is put on lock-down as the Bergen County SWAT team shoots tear gas into what proves to be a home occupied only by a cat.

In each case, the people who wound up in the crosshairs were actually victims of a dangerous and increasingly common hoax known as "swatting," so called because a bogus emergency call prompts the response of a SWAT team.

It is typically perpetrated by young, savvy computer hackers who exploit the limitations of the 911 emergency system and advances in computer technology to cover their tracks, experts and law enforcement officials say. They do it for bragging rights or revenge, but it costs taxpayers and puts innocent people at risk, experts say.