A 12-year-old boy is a murder suspect after a man in his 40s was assaulted outside a McDonald's restaurant.
The youngster was held on Sunday morning along with another youth aged 17, after the earlier arrests of two boys aged 16.
All are being held in custody for questioning on suspicion of murder, said Greater Manchester Police (GMP).
Police were first called shortly before 10.50pm on Wednesday to an assault, which reportedly began outside the McDonald's on Warrington Street in the town centre of Ashton-under-Lyne, Tameside.
A man in his 40s was found injured and was taken to hospital where he died in the early hours of Thursday.
Formal identification of the victim is yet to take place. His name is expected to be released by police on Monday.
Detective Inspector Kevin O'Regan from GMP's Major Incident Team said: "This has been quite a fast moving investigation and we have now made three further arrests, bringing the total number of people we have in custody to four.
"Our investigation continues and I would urge anybody with information to please contact police, no matter how insignificant you think it may be."
Anyone with information should call police on 101 quoting incident number 2541 or 27/07/16 or the independent charity Crimestoppers, anonymously, on 0800 555 111.