You could say something like, "I hope you're okay." If she then wants to share she can, otherwise she just will say she's fine. Then you leave it at that. Show your concern in such a way that they don't feel pressured into telling you. This really goes for any type, not just INTJ's.
I know you want to make sure you behave correctly toward people, but you don't have to walk on eggshells whenever you interact with an INTJ. We are actually human. You don't have stress about the details so much. If an INTJ reacts like a total asshole over something like this, then he/she probably is an asshole and not worth being friends with. People can't be upset with you for being respectful and nice.
Elaborate on what kind of concern you have. Is it a fear for someone's life? Is it a lot of animals that may be in danger here? Was someone sexually assaulted? There are lots of different possible scenarios here that I'm not sure there is room to enumerate all of them.
As an INTJ, I've never really need other peoples help in dealing with situations like this. Best to let your friend alone for awhile. If this goes on long enough, go try asking if you can help. :laughing: