SignalR: How to create and send message to a group from all connected group?

SignalR: How to create and send message to a group from all connected group?

i am working on a chat application. I am able to sen message to a
particular client or all the connected clients. But i want to select 4
Connnected user out of 10 connected user and send the for a common message
at a time.
Any help is very much appriciated