MAJOR help needed :(

Cats are famous for misdirected aggression. Something about that installer didnt sit right with one or both of your cats. Maybe the guy owned dogs, or had a tomcat of his own that your cats could smell. The fact that they are not fixed is definitely to blame. Get them fixed and their aggression will go down as the tom hormones cycle through their systems. Fixed males are much, much less territorial, which is what I suspect the issue is. Your cats smelled some other animal in their territory and flipped out. This caused them to fight among themselves because there was no physical cat present, only the smell. Then, the aggression boiled over to you. It is a common problem when there is a stray tomcat living near a house with unaltered cats. Get them fixed, and maybe try a feliway difusser or some feliway spray that are known to calm cats down.

Honestly, tell your parents to not even think about putting them down until they get neutered. You will be amazed at the difference without hormones. It would be very sad for two cats to die instead of them getting the most common and cheapest surgery available.

Ouch! That looks painful. I hope you've cleaned up the scratches really well and applied antibiotic ointment.

If something bothers a cat and he can't get at the source, he will frequently redirect his aggression toward another cat or person. The aggression in unneutered males tends to be especially strong.

It could have been something about the TV guy that upset them, or the timing may have been coincidence. Maybe there was another cat outside that they thought was invading their territory. Since they couldn't get at whatever it was, they took it out on each other and you just happened to get in the way.

Have they calmed down any now? If possible, I would keep them in separate rooms until you can get them to the vet to be neutered. Once they're neutered they will still have male hormones in their systems for a while, so don't expect instant results. After you bring them home, continue to separate them and do a slow introduction as if they'd never been together before.

I'm sure somebody else will be along soon with more suggestions for you. It would help if you can tell us a little more about your situation. How old are your boys? Have they always been together or did you get them at different times? Are there any other animals in the home. How much space do you have in your house or apartment?

Sending lots of calming for you and your kitties. And more calming for your parents.

P.S. Welcome to TCS.