At this link a video from IDF is published. It states that it is satellite picture of the hospital site before and after the explosion. Unless the parking lot was packed with people it is very hard to see how the explosion could have killed hundreds of people.
https://www.israelnationalnews.com/news/378710
1. What do you mean by “so many” you don’t accept Hamas’ accounts on “numbers” do you? Unless confirmed by sources. 2. If a building is destroye, of course it can kill many.