The calculated assault at a home south of Brisbane comes amid a surge of social media robberies, prompting an urgent warning from authorities.
The violence erupted when three men armed with knives demanded the residents of the Forest Lake property hand over the e-scooter on Sunday evening.
The scooter had been advertised for sale privately on social media for $2000.
Two of the alleged attackers went to the home about 1.30pm to inspect the scooter before trying to pay with counterfeit cash.
"The two males who attended the property have then produced a knife, an altercation took place which resulted in the two males leaving the address without the scooter," Detective Superintendent Andrew Massingham said on Monday.
Hours later, they came back with reinforcements and three men scaled the back fence armed with weapons including knives, machetes and a handgun later revealed to be a gel blaster pistol.
"They demanded that the scooter be produced and started smashing the rear glass doors of the property to try and entice the victims to come outside," Det Supt Massingham said.
"When that did not occur, they stabbed the dog."
Despite the efforts of police and late-night vets, the dog died.
The residents armed themselves with shovels before a violent confrontation in the backyard.
Three men aged 33, 30 and 21 were stabbed, one seriously, during the wild brawl and taken to hospital with puncture wounds.
A 33-year-old resident was stabbed in both arms, a 30-year-old was stabbed in his back abdomen and a 21-year-old was treated for minor lacerations.
The alleged attackers, aged 24, 20, and 21, have been arrested.
Two were injured as the homeowners fought back and remain under police guard in hospital with injuries including a fractured cheekbone, lacerations to the eye socket and injuries to the back of the skull.
The 24-year-old alleged attacker - a man from Goodna - appeared in Richlands Magistrates Court on Monday.
He has been charged with serious animal cruelty, attempt to enter premises and threatening violence as well as two counts of wounding.
He will remain in custody until his next appearance in October.
The 20-year-old alleged attacker - a man from Darra - will appear in Brisbane Magistrates Court on Tuesday.
He has been charged with serious animal cruelty, threatening violence, attempt to enter premises and possessing counterfeit money.
The man has also been charged with three counts of possessing dangerous drugs - including cannabis and methylamphetamine - as well as two counts of wounding.
"These attacks - in particular, this one - of people in their own home is indeed savage, ferocious, and indeed have no respect for human life," Det Supt Massingham said.
"This was a group of men intent on financial gain, using extreme measures to try and overpower and intimidate.
"These attacks occurring on persons with items for sale on online platforms is increasing."
Police officers across the state's southeast are regularly called to robberies targeting social media sellers.
"Our call to people is that if you're advertising expensive items for sale online, you take appropriate measures to ensure your safety, and if you intend on inviting people to your residence to inspect the property, there are several safeguards that you should take," Det Supt Massingham said.
Facebook marketplace offers guidelines to unscrupulous buyers and sellers, including allowing access to your home.
"Don't share your financial information or unnecessary personal information with buyers or sellers," it said.
"Don't respond to messages or emails that ask you to provide verification codes or account information, such as your email address and password."
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