Send players a message in a certain region.

Hello, I'm currently developing a arena-event plugin. Everytime a player kills somebody from the enemy team a broadcast shows the current score. This spams the chat pretty and for everybody not participating in the arena the chat becomes unreadable.

So now I'm looking for a way to only broadcast/send the message to players in a certain region.
Basically I'd imagine it going like this:
Option 1: Find players in the defined region/cubiod/chunk and send all of them a message
Option 2: Sending a message from a block and only players within a radius recieve the message.

Is it possible like that? What would you do to get the players? Is there maybe a even easier way to do this?

 

Option 1: Hook into regions plugin of choice. Get all players, get all players in region, send players a message.

Option 2: Get block location. Get player location. Get distance between locations. Check for threshold.

 

But getting all players? Won't that use up a lot of ressources?

 

There barely exist servers that can handle more than 100 players, and even if there was a server capable of handling a million players, simply sending some of them a message would still not be much.