Advice

So yesterday I was hanging out with a boy I like and he happened to asked me to be his girlfriend. Well everything was going great and as I was about to leave he calls me and says he needs to tell me something. Well he tells me that he’s having a panic attack and it was the first time I have ever witnessed someone have a panic attack. I managed to stay calm and help him calm down.

But I was wondering if any of you had any advice on how to deal with that situation for if it happens again?