A van full of kids comes screeching around the corner, glances off the side of your vehicle and caroms off into the ditch. 

The world turns upside down and you are thrown from your vehicle. Remarkably you land in a bush and picking yourself up off the ground you find you are unhurt but you see that there have been other vehicles involved and there are many injured around you.

A paramedic team has just arrived and they ask if anyone has any medical training to help them out, while they go check out the other vehicle. You tell them that you are a resident physician (PGY1 family). They leave you with three injured people to look after and give you a bag of equipment from the ambulance. They ask you to "triage these three and we'll be back as soon as we can"

What do you do first?