A 17-year-old boy is in hospital in a serious condition after an alleged street brawl involving up to 20 people in Adelaide early this morning.

Police arrested four men following the alleged brawl near Savvy nightclub in Light Square at around 1am.

Two people were taken to hospital after the incident, the 17-year-old who is in a serious condition and a 19-year-old man who is in a stable condition.

Some of the men believed to be involved in the alleged brawl were denied entry to Savvy nightclub in the moments prior to the alleged fight breaking out.

Police say they are investigating whether the arrested men have any links to outlaw motorcycle gangs.

They have asked anyone who witnessed the incident to come forward.

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