I definitely wouldn't. I've only seen 1 or 2 photos from the Boston attack and I wouldn't want strangers working on me if I was wounded. Some people jump in during those sorts of things because they just want to show others that they're good people and they have no clue what they're doing.

I saw a photo of someone applying a tourniquet. I wouldn't want someone doing that to me then finding out that I didn't need it and consequently risked losing an appendage.

I've worked with people like this. Their main goal in life is to show people that they're "do-ers" and/or proactive (because they lack in other areas) and not oblivious.

I would ask for references and qualifications first. I wouldn't want someone who couldn't pass History or Geometry working on me.