Check looking ent

[lucaspou]

i would like to do a check to se if a player is aming at a ent with his gun

i got this in my weapon

local tr = self.Owner:GetEyeTrace()

so how do i make a check to se if it is a entity and a special class
so a check that looks if it is a ent and a special class
and then exucutes a line of code

anybody can help me out :)