This seems like an example of good strategic communications. A calm response to a potentially tragic event (if as reported). Obviously it will not sooth Hamas or Israeli opponents but it seems to me that this is a good example of how to communicate bad news to the public. It is not defensive, it acknowledges the possibility of the tragedy but it implies the need for patience while an investigation is conducted and it says that Israel is taking the incident seriously. There is a lot of information packed into this little tweet.