Damage Change help?

im looking for some help with my server i want to make people be able to get a crowbar at the start. But i dont want it to damage players only the zombies that are around the map. Is there a way i can get the crowbar to damage like world props aka the zombies and not people? becasue i dont want them to be able to spawn with a weapon they can use to just kill other players.

something allowpvp 0

Do you want other weapons to deal damage to players?