The people that your friends care about are you, your DH and your DC. You are ok, and that is their concern. Your immediate family is clearly ok, otherwise most people would assume you would say something, and the grapevine would pass it on. The rest? It becomes peripheral.
When the London bombings happened I contacted my DH immediately to make sure he was safe - he was, and was on standby for support services. I then phoned my family in Australia - most hadn't even heard of the bombings yet, others had just heard that something was happening, but didn't know what. Told them what happened because I knew that as the news filtered out my extended family would all be on the phone to them checking that I would be ok (and they were, and were very pleased that DM could tell them we were all fine). But NONE of them - bar my immediately family - contacted me, or asked me directly. My DH has family here, but only a few people asked about his family. They were too much on the periphery for my extended family - that's just the reality of the situation.
Only a few people have asked whether anyone close to me has been caught up with the disasters in Australia - but it's VERY clear that I'm Australian - accent is a very clear giveaway. Most people will hear via the grapevine if something had happened - that's the reality of the situation!
If something happened to your family, your network would pass it on. Only a few people might hear it from your or say something to you, but many, many more people would be saying 'Oh my goodness, firstforthought's family are caught up in all of that, they're ok apparently though. But isn't it scary?' -Queue general concern, nodding of heads, shared sympathy, and then they slowly move onto another topic.