Did Qana Building Collapse 8 Hours After Airstrike?

The IDF is claiming that the building in Qana which collapsed and killed over 50 people didn't collapse until 8 hours after it was struck by Israeli warplanes.

If that's true, why were people still in the building?

(Note: The rescue worker in the photo to the left of this article is the same one that Richard North shows in his post on Hezbollah propaganda, as mentioned in my previous post.)