In two incidents, victims were lured to Queens Park, where one person was critically injured on Friday, May 8 and another seriously hurt on Sunday, May 10 in unprovoked attacks. Two other assaults also took place that weekend, police said.
They have not revealed the gender of the victims or the apps used.
In a statement tonight, police said the teenaged males - two 15-year-olds and two aged 16 - have each been charged with aggravated burglary following an intensive investigation.
All would be appearing in the Invercargill Youth Court on Friday.
Southland area prevention manager acting Inspector Mel Robertson said inquiries have established that there were four separate incidents where dating apps were deliberately used to lure victims to various locations, with the intent of violently assaulting them.
“This offending was deliberate, coordinated and extremely dangerous.
"The level of violence inflicted is deeply concerning, and it is nothing short of luck that the victims were not more seriously injured.
“The reality is stark - one more strike, one more kick, and the outcome could have been fatal.”
Southland police last week warned people not to share videos that had emerged after the Queens Park attacks.
Insp Robertson said police were increasingly concerned about the apparent influence of online and social media trends that appeared to encourage and glorify this type of offending.
“Let us be clear - this behaviour is completely unacceptable.
"These youths are old enough to understand exactly what they are doing, and choosing to engage in harmful, trend-driven behaviour that endangers others will not be excused, and it will carry serious consequences."
Police were continuing their investigation and further arrests and charges were expected, she said.
“We are urging the public to take care when engaging with people online and to report any suspicious behaviour immediately. If you have information, come forward. You will help prevent further harm."
Insp Robertson acknowledged the investigation team "who have worked tirelessly to identify and apprehend those responsible in a very short period of time".
"Their commitment has ensured swift accountability for those involved."
Police remained committed to protecting the community and would pursue anyone involved in this type of offending.
"If you think this behaviour is a game or a trend, you are wrong. The consequences are real - and police will hold you to account."
The Invercargill City Council last week said it was working with police and committed to ensuring that everyone felt safe in the city's parks and reserves.
Mayor Tom Campbell said he was ‘‘devastated and horrified’’ to hear of the attacks.
- Allied Media
