UPDATE: It turns out that Commissioner Bill Evans left the conference described below to be on the scene of what became a fatal fire, which took the lives of 2 firefighters.

I've been to dozens of tech conferences over the years and seen hundreds of speakers, but I've never seen such a dramatic ending to a talk as I did this afternoon at SecureWorld Boston, which took place at the Hynes Convention Center along the finish area to the Boston Marathon.

Boston Police Department Commissioner Bill Evans was presenting on what first responders did well/not in the aftermath of the Boston Marathon bombings, noting that coordination among various agencies was relatively smooth given training they had done for such events (in this audio snippet, he describes keeping cops from rushing in and shooting suspect #2 to smithereens). Cellphones were useless, but social media was extremely helpful, Evans said. This year there will be even more police presence and more cameras along the route for next month's race, which will have 36K runners, up 9K from a year ago, he noted.

listen to ‘Boston Police Commissioner Bill Evans’ on Audioboo

A 46-time marathoner himself, the then-superintendent Evans was relaxing in a hot tub after finishing the marathon in a little over 3.5 hours when he learned about the bombing. He had been asleep for maybe an hour and a half a few nights later when notified that an MIT officer had been shot by the suspected bombers. So this is a guy whose job regularly tears him away from whatever it is he is doing.

It happened again at SecureWorld, where he was interrupted partway through his talk by someone in the hallway who informed him there was a 9-alarm fire down nearby. Then, shortly before he was to have finished his speech he was interrupted again, but this time was told the Mayor needed to see him regarding the fire. And so the session ended, with a standing ovation. Little did we know then just how a serious a scene Evans would soon be visiting.