Apparently, you haven't gotten close to the end of the game. The Special Forces show up at Midnight on your last day. There are multiple Speical Forces troops in every area, except Lesuire Park and the Maintenance Tunnels.
Yes, you can kill them. They aren't that hard to beat. There are a few ways to kill them:
1: Shoot them a lot.
2: Hit them with pipes, bats, torsos, 2X4s, etc. a lot.
3: Slash them 1 to 2 times with the Small Chainsaw (Next To Best Way To Kill Them)
4: Shoot them one time with the Real Mega Buster (Best Way To Kill Them)
5: Run them over with the Motorcycle (Very Fun)
6: Shoot a tank they are close to.
There may be more ways to killing them, but I can't think of any right know.
If I'm not bad wrong you get 5,000 PP for killing 1, it may be less though.
[Edited by SJS2006, 9/27/2006 4:00:54 PM]
My favorite way to kill them was to use the move Disembowel. You don't actually pull their guts out like you do to zombies, but it still takes them down just as quickly. That, and the Face Crusher move make for some fun times with your Special Forces buddes.