I try to avoid the Pain Olympics, i.e. my pain is greater than your pain, because… but I can at least say that I’ve been through some legit crises. As such, I can now call myself a Certified Pain Expert, and can advise you as such.
In line with that, don’t try to be helpful about the silver lining. “Well, at least you still have ONE leg!” No.
One of the things with crisis is, it is all consuming. When you’re in it, nothing else matters. People in crisis often move into survival mode, where everything else is stripped down, so they can devote all their strength and mental energy to surviving. That is why it’s not a good idea to ask them to call you and update you on the status of their tragedy. No. Find a relatively stable contact person, who is on the close outskirts of the situation but not actually wearing a hospital bracelet, and get updates from them. Or if there are general updates online, work with those. People in crisis will tell you the nitty-gritty when they’re ready.
Hug them, pray for them, and most of the time, don’t offer advice. Odds are good that you don’t know what you’re talking about.
Ultimately, you will do some things right and some things wrong. The important thing is to be there, physically or emotionally, however the person in crisis prefers to be supported. Good luck!