I was always taught to call 911 first if it looks as though people are injured, the faster they are notified the faster they can get there and help, usually it is better to send someone to call 911 why you do the rescue aspect. From there I would throw flares out since it can be done fast and improves my saftey and the saftey of the injured, after all I am no help if I get hit myself. From there I would extinguish whatever flames I could and then check the people out and triage them on the severity of the injurys and what I could do for them.

That is what I would do, however being im no professional, I don't know if that is proper procedure. I'm just using what I learned as a Boy Scout and from my CPR/Defib training.