It's known that their hospital system has servere levels of over crowding, and the article states both that:

The video shows cots, blankets, and other personal belongings on the grassy area. Taken together, these two videos indicate that it was likely occupied by people who were resting or sleeping there at the time of the explosion.

And that:

Other images from the parking lot of the hospital show widespread damage to vehicles in the parking lot, including one that was flipped over onto its roof. Another vehicle nearby shows signs of extensive damage, while others show evidence that they were engulfed in flames.

...an over crowded space, babies in cots, with an explosion large enough to flip a car, near one of the few areas with grass soft enough to sleep on.

Plus a fire.

Plus due a hospital low on supplies, low on water, in need of emergency power... Could probably kill hundreds, and cause the death of more.

If the hospital had some structural damage as well. Could probably do plenty of killing. The article doesn't nominate a number, so I can't speak to your source on that.

This is the thing I've been thinking about a lot. I definitely wouldn't have wanted to be anywhere near that explosion, but aftermath sure doesn't seem to line up with "500 people killed in hospital collapse caused by explosion". I don't even see a collapsed building in the panorama shot. Somebody's lying their ass off, and I have no idea who it is.

Estimation at best. They probably knew about 500 people were there, but had no idea of a body count.

That being said, a lot of people were sleeping in the grass next to the impact site, and some in the parking lot. They are estimating around 200-300 people. Some of the people in the grass were already dead.

But most were using it as temporary sleeping area due to the destruction of their home.

Last point I'll talk about is that this crater was not caused by an airstrike like Hamas claimed. And the hospital is not destroyed which they also claimed. And the ballistics show that it would have come from not Hamas, but the other faction in the region, the Islamic Jihad group territory.

It seems I owe a few people here an apology.

The other issue is that Hamas released that death count less than thirty minutes after the explosion. There's no way to get an accurate number that quickly.

A pretty plausible scenario is that they realized the fuck up, which probably did cause an extensive number of casualties given that the courtyard was apparently full of civilians, and immediately pushed a story about Israel catastrophically bombing a hospital in order to deflect attention, in hopes that western media would repeat the story without question, which was of course a correct assumption.

Video of the aftermath. It's horrific. ~500 is accurate. When half of them are children it doesn't take up as much space as you think.

Bellingcat is usually pretty damn good reporting.

Bellingcat is on it.

People keep saying this but it's not true. Here's a case from 2014 where the consensus is the munition was Israeli, with the eyewitness account of a NBC reporter. The impact was also indirect. The excuse is even the same, they blamed 'Gaza terrorists', not Hamas directly. That doesn't mean its the same this time but it's not a given that Israeli munitions would simply level the hospital.

https://www.vanityfair.com/news/politics/2014/07/gaza-shifa-hospital-bombing

This is a good way to analyze the situation: https://youtu.be/l29IRT16zq0

May have been a small diameter bomb.

Israel uses them in Gaza all the time.