Four teenagers have been injured after an incident outside Oldham Leisure Centre.
It is believed they have been stabbed and their injuries are thought to be serious but not life-threatening.
All four are male and are aged between 16 and 19 according to Greater Manchester Police.
Emergency services were called to the area at around 4.30pm yesterday and the area around the centre has been taped off.
A 19-year old man has been arrested on suspicion of Section 18 assault and remains in custody for questioning.
Anyone who may have information about those involved, please contact the police on 101 quoting incident number 2093-14/11/19 or Crimestoppers, anonymously on 0800 555 111.