Killing a player who is on the same team as you is known as "team-killing". TKing is frowned upon amongst players and it is customary to send an apologetic message after accidentally doing so. Maps are sometimes configured to destroy you if you TK and/or kick you for repeated TKs. Deliberate TKers are a nuisance and will most likely earn themselves a kick or ban from server admins.
Players who believe they are being victimised and deliberately TKed should send a message during the game asking the offender to stop. Try to stay calm and objective - the offending player may be new to the game and not realise what they are doing. If it doesn't stop, go somewhere else or switch team, then delight in shooting them back!
Note that rogue is not a team - they can shoot players of all team colours including other rogues.