Another attack came on the night of 15th. The US Navy supply ship, USS "William Ward Burrows" (AP-6), had arrived at dusk to drop off supplies meant for the Marines stranded on Wake, and to retrieve some civilian contractors to return to Pearl Harbor. The Navy ship and the Marines on Johnston spotted a flash at sea. The first enemy shells hit Johnston and its powerhouse, setting off a large fire that engulfed the building. The Marines returned fire for ten minutes until the submarine ceased firing.