HELP! my cats are killing each other!

at about 8:30 this morning I got home and noticed the neighbor's cat was sleeping on my back deck. I don't particularly care, so I just left him alone. When I got in the house, all 3 of my cats were just watching him through the back window. I left them alone because I didn't think anything of it.

Suddenly there was such a commotion coming from the back door. The neighbor cat had woken up and was banging at the door, trying to get in. My cats completely freaked and started taking out their agression on each other. They are hissing, growling, bristling, and making some of the most horrible sounds I have ever heard, not to mention beating the living hell out of each other. I can't put them near each other. it's 3pm and this has been going on since 8:30 this morning. I'm afraid one of them is going to get hurt. What should I do?

Separate them and let them calm down?

Thanks... I tried that for a couple hours and it didn't seem to work. They just started right back up again as soon as they saw each other.

You need to do it for a day or two - that's how long it usually takes (for redirected aggression to be forgotten about).

You might even have to go through the introduction process again (you can use the forum's search function for lots of good tips on that). I would give them their space for a few days, then slowly let them re-meet and see if the time has solved the problem.

yes, keep them seperated as long as you need to. also, many pet stores sell a product called comfort zone that might help... it's made by the people who make feliway (don't recall of the top of my head if it actually has feliway in it or not, but) it works like a plug-in air freshener to fill the room with calming goodness for kitties... try putting a few of those around your home. using a drop or two of vanilla on the kitties can sometimes help, too... the scent of vanilla overpowers their individual smells, so they don't get triggered by the smell of each other.

good luck, mate :/