Grey disk like craft no sound no lights moving around 300 feet altitude at high rate of speed westbound just 100 feet southerly of Grant rd running parallel. Came very close to a landing emergency medical helicopter landing at TMC hospital maybe only a couple hundred feet from the helicopter on its approach. There was an aircraft that seemed to be following but was about 10 to 15 miles out. Recon and tracking as it followed the same flight path. My statement is true to the best of my ability in description and memory.