Two 14 year old boys who were arrested have now been Released Under Investigation pending further enquiries.
A 15 year old girl, a 16 year old boy, a 33 year old woman and a 37 year old man all remain in police custody.
Police are not yet in a position to name the boy who has died.
If anyone has any information about the incident, or if you saw a group of teenagers in the Fulford area of York in the early hours of Sunday 28 September, please get in touch with police.
Dial 101, press 1 and pass information onto the Force Control Room, quoting reference number 12200169915.