Forty heavily-armed members of the Bergen County Police Department SWAT team surrounded a New Jersey home after responding to a caller who claimed he had already killed four people and had taken several hostages inside the house.
After a tense three hours, the police commander on the scene gave the order and the elite SWAT unit tossed tear gas grenades into the home before rushing in, guns drawn in preparation for a fire fight. But inside they found no dead bodies, no hostages and no madman -- just a cat.
Only later did police find out that the July 24 incident was all an elaborate prank allegedly set up by the hacking group Anonymous. They had targeted that particular home because it belonged to Parry Aftab, a cybercrime expert who has spoken out against online bullying techniques, including those used by Anonymous.
Anonymous, an online community with no hierarchical organization, has made headlines the world over for a string of high-profile hacks the group claims to have carried out -- from allegedly hitting the websites for Paypal, Visa and Mastercard to name a few.
But behind the headlines, a large and unspoken share of the group's activity is focused on smaller-time efforts, "life-ruining" tactics to target individuals, said Cole Stryker, the author of "Epic Win For Anonymous: How 4chan's Army Conquered the Web" and one of the group's newest targets.
"It's a power thing," he said. "It gives social misfits the opportunity to lash back at society."
A London-based member of Anonymous who spoke to ABC News and asked to be identified as Chelsea Meader said harassment of individuals is as common in the group as "checking your email."
"If you look at the [Sony] PS3 hacking and recent arrests, that could be pinned down to 100 people doing the serious stuff that made the headlines," he said. "The majority of Anonymous work is just harassing people. You're young and spiteful and you've got this little bit of power and no one knows who you are."
Stryker is one of the latest targets to draw ire from some self-ascribed Anonymous members, including Meader, who said he disagrees with Stryker positioning himself as "some sort of expert" on the group. Meader compared Stryker's book to a "short story on terrorism passing itself off as a history of Islam."
In a community where anonymity is the paramount rule and computer screens are shields, people tend to move to the extremes of human behavior, Stryker said, calling the Aftab incident "the most dangerous thing Anonymous has done."
Stryker knew what to expect as soon as he found out his address was publicized on Twitter last week.
In the days since, he has been sent a deluge of direct mailings, magazine subscriptions he didn't request and confirmation emails saying products he didn't order are on their way to his Manhattan apartment.
Violent threats have been splashed across his Facebook book party wall but so far they haven't amounted to anything.
"Sometimes their bark is bigger than their bite," he said.
But the harassment has crossed over to his family, who have taken on the burden of Stryker's newfound prominence with Anonymous.
"They sent my 60-year-old aunt a message saying I wanted to pursue some sort of sexual rendezvous," he said.