FireServer can only be called from the client??

I made this script but im not sure whats wrong with it. IT keeps giving me the error "FireServer can only be called from the client" And it is NOT a local script. This script is in server script service.

local rep = game:GetService("ReplicatedStorage")
local event = rep:FindFirstChild("Events").Kill1
local target = workspace.Quest1:GetChildren()

for i, v in pairs(target)do
	if not v:FindFirstChild("Humanoid")then
		return
	else
		if v:FindFirstChild("Humanoid")then
			v.Humanoid.Died:Connect(function()
				event:FireServer()
			end)
		end
		end
end

local function working()
	while wait(1)do
	print("hi")
	end
end

game.ReplicatedStorage.Events.Kill1.OnServerEvent:Connect(working)