A teenage boy has died and three other teenagers have been released from hospital following an "incident" in a field, police have said.
They received reports about the boy's welfare near Dewhirst Road, Rochdale, shortly before 11:15 BST on Saturday.
"Inquiries into whether there were any suspicious circumstances around this boy's death are ongoing," a Greater Manchester Police spokeswoman said.
Anyone with information has been asked to contact police.
A post-mortem examination is due to take place later this week.