Use tentacle attacks to keep Carnage at a distance. If you can get close, use claw attacks which are more powerful. Feed on the policemen on the scene to regain health. When Carnage escapes to the next room, go to the door with the blue circle and press Grab to start a door opening mini-game. Carnage will recharge his health a few times during this fight so continue to feed on the policemen. Watch for Carnage's spinning tentacle attack and jump out of the way.