6 month old male kitten ran away?

He actually went missing the day before he was supposed to get fixed, hes not way to old to be not fixed, i've talked to a vet about it before 5-6 months there supposed to get fixed. And yea its possible he got hit by a car and they took him away right away while i was not around. So im not sure i dont think i can call anyone about that cept for the vet whom i did call.