It is only because it was a gut shot.
I bet they never catch the cross-bow guy, they deal damage almost as well as a hand gun but no one ever hears them go off ... which is what usually leads to someone witnessing a shooter and their eventual capture.
Makes me wonder what they were doing driving around with a cross-bow in their front seat to begin with. Hunting?
‘Hunting’ the asshat who hit his car with a rock. maybe?
Crossbows are the preferred weapon of choice when hunting zombies.