Button1Down function not looping damage?

When the player clicks down the button and holds it, the damage will continue to happen when they are being clicked over. The problem is, the script only damages the player once

player = game.Players.LocalPlayer
character = player.Character
gun = character:FindFirstChild("Rifle")
mouse = player:GetMouse()
auto = false
function getModel(raw)
    for _, child in pairs(workspace:GetChildren()) do
    --calling pairs is barely any slower than using next directly, plus it's easier to read.
        if raw:IsDescendantOf(child) then
            return child;
        end;
    end;
    return nil; --this allows us to not use pcall
end;

mouse.Button1Down:connect(function()
	auto = true
	while auto do
    if mouse.Target then
        local model = getModel(mouse.Target)
        if model and model:FindFirstChild("Humanoid") then
            model.Humanoid.Health = model.Humanoid.Health - 15
			wait(1)
	end
mouse.Button1Up:connect(function()
	auto = false
end)
        end
    end
end)