Problem with camera script

The code I use for my script is this:

if uis:IsKeyDown(Enum.KeyCode.D) then
		camrot *= CFrame.Angles(0,math.rad(1),0)
	if uis:IsKeyDown(Enum.KeyCode.A) then
		camrot *= CFrame.Angles(0,math.rad(-1),0)
	if uis:IsKeyDown(Enum.KeyCode.W) then
		camrot *= CFrame.Angles(math.rad(1),0,0)
	if uis:IsKeyDown(Enum.KeyCode.S) then
		camrot *= CFrame.Angles(math.rad(-1),0,0)
	cam.CameraType = Enum.CameraType.Scriptable
	cam.CFrame = hr.CFrame*camrot*,0,camzoom)

And when I print the eularangles of camrot, the Z axis changes and it starts moving the camera sideways. How would I fix this?

Is there a way to rotate on world axis with scripts? This is what I mean by it rotates sideways btw.