Well, what they did is SOP for our anti-terrorist forces when they think they might be dealing with someone holding a bomb trigger. They famously did the same to three IRA players in Gibraltar some years ago.
"Witness 2) I should say they were from a distance of about four feet and that the firing was continuous; in other words, probably as fast as it's possible to fire."
http://www.museum.tv/archives/etv/D/htmlD/deathonthe/deathonthe.htm