I was on a radio show earlier today (the "Your Call" show on KALW, a local public radio station in San Francisco) when a man called in to tell how he had successfully built his own armed drone, using commercially available equipment. He did not use a real gun, but a paintball gun (many paintball guns are comparable to real guns in weight).
The man referred us to this video, which he has posted to show his experiments with his armed drone. The man, who calls himself "Milo Danger," appears in the video wearing a bandanna to hide his face and with his voice apparently electronically altered.
Although not shown on the video, on the radio call-in "Milo" said that he had used it to shoot not only at stationary targets but also at live human beings. In response to a somewhat incredulous question from the host, he assured us that they were fully consenting volunteers. In general, he appears to be making an effort to spark awareness and discussion of the technology's potential in a responsible manner.