a timed zombie spawner?

Hi, I'm making a Roblox game where the goal is to survive zombies. I've already coded the round system and now I just need a script to make a timed spawner that limits how many zombies can spawn on a spawner and kills all zombies when the round is over also you will be featured if you give an answer bye!

@luxkatana here's the round script it must be inserted in severscriptservice

local roundLength = 300

local intermissionLength = 15

local InRound = game.ReplicatedStorage.InRound

local Status = game.ReplicatedStorage.Status

local LobbySpawn = game.Workspace.LobbySpawn

local GameAreaSpawn = game.Workspace.GameAreaSpawn

InRound.Changed:Connect(function()

if InRound.Value == true then

	for _, player in pairs(game.Players:GetChildren()) do

		local char = player.Character

		char.HumanoidRootPart.CFrame = GameAreaSpawn.CFrame

	end

else

	for _, player in pairs(game.Players:GetChildren()) do

		local char = player.Character

		char.HumanoidRootPart.CFrame = LobbySpawn.CFrame

	end

end

end)

local function roundTimer()

while wait() do

	for i = intermissionLength, 0, -1 do

		InRound.Value = false

		wait(1)

		Status.Value = "Intermission: ".. i .." seconds left!"

	end

	for i = roundLength, 0, -1 do

		InRound.Value = true

		wait(1)

		Status.Value = "Game: "..i.." seconds left!"

	end

end

end

spawn(roundTimer)