Police were called after a varsity rugby match between the universities of Sussex and Brighton descended into violence.
Spectators were injured after rival groups of fans spilled on to the pitch and became embroiled in a mass fight.
Bottles were thrown, banners of opposing fans were set alight and flares were let off.
One student reportedly threatened another with a knife, according to The Times.
People were also abused with homophobic, misogynistic and racist language, Sussex student union said.
In a joint statement, Adam Tickell, vice-chancellor of the University of Sussex, and Debra Humphris, vice-chancellor of the University of Brighton, said: "The scenes witnessed at the annual Varsity sports day were shocking and disgraceful.
"A full investigation has been launched into events and any students identified as having participated in the disorder will face serious consequences under our codes of discipline. We unreservedly condemn the behaviour.
"The future of fixtures will be under review as part of our wider investigation."
A small number of spectators were injured and received first aid on site, while some were taken to hospital as a precaution.
Police said one person had been arrested on suspicion of carrying a weapon, but later released.