I have no clue what happened here but there was definitely no one shooting at me, it looks like my own bullets hit me
(i saw exactly the same in a twitch stream yesterday)

https://www.youtube.com/watch?v=-ftxObFVF5c&feature=youtu.be

Maybe he kill you and you had desync, he had a lot of time to kill Y.

but he had nothing in his hands :/

I asked the other guy i the video and thats his point of View: