Fourteen men who were arrested after a brawl outside a college have been released on bail.
CCTV footage of the area is being reviewed
Three people were stabbed when violence erupted outside Havering College in Hornchurch, Greater London, on Monday afternoon.
Two 18-year-old men were critically injured. One is now in a stable condition and the other was well enough to go home on Tuesday night.
A third 18-year-old remains in a stable condition in hospital.
Police said those arrested were aged from late teens to over 40 and must return to a police station next month.
Knives were recovered by police near the scene of the fight and CCTV footage of the area is being examined by officers.
Detectives said it was not being treated as a racially motivated incident and they were keeping an open mind as to why the fight started.
Havering College, which has about 14,000 students and offers further and higher education courses, has confirmed one of the victims was a student there.
Ch Supt Sultan Taylor said: "Up to 20 people were involved with the incident and while we have made a significant number of arrests some suspects remain outstanding and we are working hard to trace them."