Um, there are other people raising hell, too. I havn't played it myself, but I've watched others play and encounter other gangs doing drive bys and getting smacked down by the police.
You ought to get it. Amazing game. Amazingly big and open-ended. When I got it, I spent about 5 hours just driving here and there, swimming and trying ecerything out. Then I realised about the countryside. And the cows. Moo BANG!!! He he.
I'm kinda pissed at the moment though. I started doing missions last night. Managed to unlock San Fierro, and then my PS2 crashed. And I lost everything. Gotta start again now. Oh well, even more fun!!!