The attacks have been aided by forums that have sprung up both on the public internet and on the camouflaged sites of the so-called dark web. These forums name thousands of people, from high-ranking executives to their extended families, who could be targets, providing cellphone numbers, home addresses and other information. Some even discuss techniques that can be used — like cheap, online technology that can spoof a phone number and make the police believe a 911 call is coming from a target’s home.

In the eight months since one online forum was started, nearly 3,000 people have joined.

“Who should we do next?” read one message on the forum last month. The responses included gun emojis — the symbol, in swatting forums, for an attack in which the police were successfully called to the target’s home. Many of the responses were laced with profanity, as well as suggestions for ex-girlfriends who should be swatted.

One forum names at least two dozen Facebook employees as potential targets. They range from executives to product engineers. Some forum participants said that they had been barred from Facebook or Instagram, and that Facebook employees were fair game because they “think they are god.”

On another forum, new names of potential swatting victims are added daily. With each new entry, there is — at a minimum — a home address. Some entries contain more details, including the best time of day to catch the person at home or information about the children’s school.

“Lol, sick,” read many of the replies.

Swatting started in the combative world of online gaming. It was a way to terrorize someone more famous, get even with a rival or retaliate against someone with different political views.

Provoking a heavily armed police response presents obvious risks. Last year, a 26-year-old California man was sentenced to 20 years in federal prison for calling in dozens of fake emergency calls, including one that led to the fatal police shooting of a Kansas resident, Andrew Finch.