It was the assistant coach in the cave. The head coach was alerted by the parents.
From that paper I had read (Perth, Australia):
“Family members raised the alarm later that day. Where were they?
Their parents’ concern drove their coach 25-year-old Ekapol Jantawong, a stateless orphan who shared their love of football, to the cave. Near the entrance, he found their bikes, a discovery that meant he had to go deep inside to try to locate them and bring them back.”
Who knows? Perhaps the parents told them “their coach went”, and the reporter added the part about Ekapol, and not realizing he was the assistant coach?
It seems odd that if they new they were in the cave, why did it take 9 days to finally get to them? Although I’m sure there are all sorts of different pathways in that cave system to search.