I noticed at first a whistling that was just odd. Sounded neat but no reason to panic. When there were responses to the first I thought maybe it was homeless trying to communicate safehavens in the apartment complex I currently guard. When the "songs" reached 5 intelligent communicators I saw what seemed to be a disc object, massive, approx 300 meters in radius. It had a single light at the base which flashed to reveal a sort of "webbing" that covered the hull. As part of my job I had to move away when it ascended above cloud cover, there are check in points for me to use every hour. Hit the first no problem but still hearing communication in "song" form. On my way to the second, 2 "songs" began to move from west of my position heading north. The other 3 were stationary south, south east and south west, respectively. When these 2 moved to my west I changed to an intercept course thinking these were homeless or vandals. To my surprise 2 bipedal, fully clothed in a grey/silver uniform (they were identical so I assume a uniform) cam from behind cover and sprinted across a road becoming backlit from a streetlight. Full helmets negated view of facial structure. When I pursued and called local authoritie" then all 5 "songs" erupted and moved west. I gave chase and when the wind kicked up very suddenly I lost both and the "song" has ceased shortly after there was increased military aircraft traffic. Mor details can be provided.