Three teenagers have been charged and South Australian police are hunting at least 30 more over an alleged ‘fight club’ operating in Adelaide’s north.

The boys, aged 14 and 17, were on Tuesday charged with fighting in a public place, with a 13-year-old girl hit with the same offence on Wednesday.

WATCH ABOVE: Police charge teenagers over Adelaide fight club on social media

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It comes after police launched an investigation into the allegedly pre-planned fights following a 7NEWS report into the South Australian fight club social media page.

The South Australian Fight Club has shared dozens of videos of fights at various locations across Adelaide, including public sports fields in broad daylight.

In disturbing footage, a knife appears to be pulled during at least one of the fights.

Police on Wednesday said that they are close to locating more of those involved.

“We have another four people who have been identified as a result of our investigation so far,” SA Police Commissioner Grant Stevens said. “We are actively pursuing those people and one of those people we believe is involved in the organisation of these activities.”

But the club has already hit back on social media, posting that police are “doing anything but catching real criminals” and the organiser has “no regrets”.

Two teenagers have been charged in relation to an Adelaide fight club Credit: 7NEWS

One of the locations — Ridley Reserve — is used by the Central Districts Softball Association in Adelaide’s north, with the club concerned about the fight club may affect their family community.

“This is the home of where we play and it’s not a safe activity for us to be around,” Kay Benger from the softball club told 7NEWS.

“What’s stopping them from coming over here and starting a fight with us?”

Police say they believe at least 30 people are involved in the club but can’t confirm whether adults are assisting in organising the fights.

— With Olivia Gilmore-Rankine