If you've had a first aid course, and can still remember what you should do, then it would have been appropriate to go and help. Otherwise, try to talk to the guy, but don't touch or move him unless absolutely necessary - if you don't know what you're doing, you could make things worse.

I've been involved in a few emergencies in Switzerland, and I've always found the Swiss to be very helpful and competent. It seems that being able to help breaks through their normal reserve.