Instinct 1 for me would be to help in any way I could. ; I'd consider taking photos only on my way to help, after I've helped, or if I was asked to not help and make way for first responders once they've arrived to help.
I've been there before - though admittedly in the days before cellphone cameras and digital. ; In 1994, Northridge Earthquake, and I was within 6 miles of the epicenter, where we were hit hard. ; I was an avid photographer and was always taking photos and had my camera nearby...I still spent the first 10 hours after the disaster event helping however I could, and didn't get around to taking photos until the following day.
After our trio of hurricanes, of which two were serious enough to cause damage throughout my neighborhood and town, I took some photos - during the hurricane, and right after each. ; I went for walks in my neighborhood with my camera to survey damage and see what I found. ; But I always stopped and put the camera down to lend a hand cutting down a tree, clearing debris from front doors to help people out, helping clear the roads, and anything else I could do. ; Photography was something I did when there was nothing else useful or contributory I could do - as I still had a desire to document the event as much as possible.
I don't mind seeing video of folks at the Marathon who were filing already, then kept filming as the blasts went - they were just as shocked and surprised as anyone, and kept filming probably without even thinking much about it. ; Most seemed to trail off their filming, or start helping, after a few minutes as things started to soak in as to what happened. ; The only ones I mind are when a dozen people are all trying to help dozens of injured strewn about, and you see one person with a camera walking amongst the downed victims and rescuers, taking photos even as people are yelling out for help or assistance. ; I've heard the argument of a journalist's duty a thousand times, but the human side of me cannot make sense of it - to not offer any help when you are capable of doing so. ; Probably why I couldn't be a journalist.