Uncle got scammed..not sure how to help.

I found out my uncle got scammed...big time...with some stocks he purchased from people in Hong Kong. I don't know the whole story as he doesn't want anyone to know but he had told some info to my mother.

He had apparently met someone who is either a broker or works with one and lives in the states (uncle resides in Canada). That person works with another person who resides in Hong Kong who had told my uncle about some stocks in Hong Kong and he ended up investing..a lot. Apparently, my uncle had contacted them (either the guy in the states or Hong Kong) and said he wanted to pull some money out after it had grew a significant amount and they told him that he would have to pay them a certain amount of money (6 figures, not sure exactly how much) to have them release the money. He had apparently told them to take the amount out of his earnings and they had told him that he would have to pay separately and they're unable to take funds from his earnings. He refused and since then, they have been ignoring his calls and emails. He had apparently paid them this money via EMT through his bank.

He wants to go after them but of course..us thinking it's a pure scam, he'll either get shot or best case scenario, not be able to find them..anyways. is there anything he can do in this type of situation or anyone he can go to? He said he would go to the embassy of Hong Kong and US but I don't see them doing anything.

Any suggestions? Or is he just fucked?

Edit: I want to thank everyone for their support, truly appreciate it.