Alpine Travel Trailer I Am Hosting A Ski Trip? Who Bears Liability?

I am hosting a ski trip? Who bears liability? - alpine travel trailer

I plan a ski trip on 2 February organize in March 2008
Alpine Meadows Ski Resort in Tahoe, California. I intend to
about 40-50 visitors. Most of them
more likely than older children. If one of them injured in the bus
Ride in a way that the quality would travel
Responsibility or me. (This is the bus company I use).
If somehow injured while skiing at Alpine Meadows
Alpine Meadows is the responsibility or mine?

Basically, I was wondering if I am to buy a certain type
Insurance?