Russian news sources really can't be trusted, but assuming it is true, it's certainly a tragedy that civilians were hurt. And I wish they hadn't been.
The solution though is for civilians to leave Crimea. They are on illegally seized land, not wholly dissimilar to Israeli settlers. It isn't their fault that their children died of course, but they need to leave the area. Issue is, Russia probably won't let them, because they'd prefer civilian casualties to occur.
It's also kinda rich of Russia to complain about this after they've bombed, killed, and orphaned countless Ukrainian kids. They've even kidnapped some of them. And from what I recall happened in Mariupol, they might've even done ethnic cleansing. It doesn't excuse Russian civilians being killed, but Russia has absolutely no legs to stand on here.