did u tell ur parents what's happening? did u talk to the principal at ur school?
if u didn't by now then do it ASAP!
stalking is a very serious issue I don't want to scare you but I want u to know that u must be extra careful.
few things u should know about stalking:
1. the stalking will only escalates.
2. even if u did tell them to back off and they're not ur friends they won't listen they are obsessed with u and the odds are they have an imaginary relation with u, don't talk with them and don't greet them.
3.RECORD EVERYTHING: I mean every time u see them write it down, u changed roads and they were there at 4 pm write it down u will need those as a proof that u're being stalked. If they call u record the calls install an app for that.
4. with time they can be more violent, try to avoid being alone.

please take this issue very seriously it's been happening for years and they won't leave u alone. u should inform ur parents, school authorities and cops too. don't face them while ur alone or curse them or be violent cuz that may trigger them in a bad way.