What do I need in a script that kills all humanoids after 5:00, and is on a continuous loop?

I have been trying to use the countdown clock gui that roblox gives out for their capture the flag game, and attempted to make the script kill all humanoids at the end of the countdown: (0:00). Could someone please help me find out how to put the two scripts together correctly, or help me make a new one? If you could, that woul be great, thanks!

local minutes = 5 -- What the timer starts from
local seconds = 00  -- What the timer starts from
local min = minutes
local sec = seconds

function killPlayers()
	local a = game.Players:GetChildren()
	for _,v in pairs (a) do
		v.Character:BreakJoints() -- Kills the player
	end
end

while true do
	wait(1)
	sec = sec - 1
	if sec == 0 then
		min = min - 1
		if min == 0 then
			killPlayers()
			min = minutes
			sec = seconds
		else
			sec = 59
		end
	end
	local count = min.. ":" ..sec
	Gui.Text = count
end

That should work. Do you need me to explain it for you, or do you have it?