Flashing lights and eerie mechanical sounds

I was on my phone in bed when I noticed a flashing light coming from outside the window next to me. Immediately after the light, I heard a weird mechanical type of sound. Sounded like something grumbling or a cog in a machine moving. Both the flash and the sound lasted a second each. A few seconds later, another flash happened followed by that same mechanical sound. Both flashes occurred within around a 10 second period.