My Dad visited the World Trade Centre on September 10th 2001. He was elsewhere in the City on the day, thankfully, but due to the disruption he wasn't able to get in touch for 3 days.
I was working in McDonalds, and just as the lunch rush was coming down we ended up crowded around a small TV watching things unfold.
I was able to lean into the fact that it was extremely unlikely my Dad was hurt, and that the reason for not hearing from him was the overwhelmed network. Phones and the internet were not good 22 years ago. A quiet work day came to an end and I went to see Alien Ant Farm play in the evening; it was very clear that they didn't want to be there.