also throw whatever you can find at the shooter; PREVENT HIM FROM GETTING A CLEAN SHOT.

edit: I just had another thought: If for whatever reason you cannot hit him (maybe he's protected by a building and he's peeking through a window), you could also just simply throw objects in front of him, obstruct his line-of-sight. One might argue that this would get in the way of Counter-Snipers, but the ultimate goal is to prevent the bad guy from shooting the good guy(s). Other LEOs/S.S. can take care of the badguy if the Counter-Sniper can't blow his brains out, maybe they could even capture him alive and interrogate him later.

also throw whatever you can find at the shooter; PREVENT HIM FROM GETTING A CLEAN SHOT.

edit: I just had another thought: If for whatever reason you cannot hit him, you could also just simply throw objects in front of him, obstruct his line-of-sight. One might argue that this would get in the way of Counter-Snipers, but the ultimate goal is to prevent the bad guy from shooting the good guy(s). Other LEOs/S.S. can take care of the badguy if the Counter-Sniper can't blow his brains out, maybe they could even capture him alive and interrogate him later.

also throw whatever you can find at the shooter; PREVENT HIM FROM GETTING A CLEAN SHOT.