Horn problem

["John North" <johncnorth@gmail.com>]

Last night, I started the car and the horn started blaring.   Removed the
horn push, still blaring.   Eventually the fuse blew before I could get to
the horns to pull a wire.   Guess something shorted out...   So now I have a
bit of a dilemma - it doesn't seem like I can use the standard trouble
shoot, per Dan Masters, because something in the circuit is blowing the
fuse.   Do I have to replace the relay or the horn, if so which first?

Any help appreciated.

John North