An explosion at the al Ahli hospital in Gaza on Tuesday evening killed scores of Palestinians.

Here is what we know so far.

What happened at the hospital in Gaza?

There was a strike on al Ahli al Arabi hospital in Gaza City on Tuesday evening, around 7pm local time.

The exact number of people killed in the blast is, at this point, unclear.

Gaza’s health ministry said at least 500 people were killed. The Israel Defence Forces (IDF) suggested this number was inflated.

Video from the Associated Press of the hospital showed its grounds strewn with bodies, many of them young children, as fire engulfed the building.

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What has Hamas said?

Hamas released a statement after the blast calling it a “crime of genocide” as it blamed it on Israel.

The militant group said: “The horrific massacre carried out by the Zionist occupation in the Gaza City’s al Ahli hospital which left hundreds of casualties, most of them displaced families, patients, children and women, is a crime of genocide that once again reveals the ugly face of this criminal enemy and its fascist and terrorist government.”

What has Israel said?

Israel has denied it was responsible for the blast, claiming the Palestinian Islamic Jihad (PIJ) militant group hit it with a misfired rocket launched from Gaza at 6.59pm local time.

Overnight, the IDF posted a video allegedly showing a rocket failing and falling on to Gaza at the same time the al Ahli hospital was hit.

In a news conference on Wednesday morning, IDF spokesperson Rear Admiral Daniel Hagari said the army determined there were no air force, ground or naval attacks in the area at the time of the blast.

He also said there was no direct hit on the hospital. Instead, he said, a PIJ rocket hit the car park and ignited vehicles.

Israel claimed the craters caused by Israeli munitions were not present at the hospital and released images it said backs this up.

Videos and stills of the damage geolocated by Sky News match the location shared by the IDF.

Sky News has been unable to verify the claims the damage does not match the craters an Israeli missile would have caused.

Audio released by Israel purportedly shows two Hamas militants discussing the incident and saying the missile belongs to the PIJ and was fired from a cemetery behind the hospital.

Sky News cannot independently verify this audio from Israel.

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What has the Palestinian Islamic Jihad said?

The PIJ, a smaller militant group in the Gaza Strip, said it had no involvement in the blast and that Israel was responsible.

Strike ‘probably’ an accident from within Gaza – analyst

Defence analyst Michael Clarke told Sky News the balance of probability points to Israeli claims being true – that the PIJ misfired a rocket.

When pressed, he put the probability at 60-70%.

The Iron Dome system allows Israel to track rockets headed toward Israel, which makes IDF’s assertion that it knows missiles were fired from behind the hospital “plausible”.

The keys to certainty are whatever missile fragments remain on hospital grounds, he said. These can provide 95% certainty as to where the missile came from – but they are under Hamas’s control, he said.

“I would expect Hamas to produce some sort of Israeli missile at some point derived from somewhere and say ‘this is the missile that hit the hospital’, and that may or may not be true.”

US independent assessment finds PIJ likely caused blast

The US has an independent assessment that it was a PIJ rocket that misfired and hit the hospital, two senior officials have told our US partner network NBC News.

This would match what Israel has said caused the blast.

The assessment was based on “analysis of overhead imagery, intercepts and open source information”, White House National Security Council spokesperson Adrienne Watson told NBC News.

Can rockets misfire?

Middle East correspondent Alistair Bunkall said, without making a judgement on the hospital strike, that rockets launched by Hamas and the Palestinian Islamic Jihad have been known to “misfire and they do land short”.

Do militant groups have rockets that can cause this damage?

Bunkall went on: “People are pointing out that when Hamas or Islamic Jihad rockets hit parts of southern Israel, they never really make the sort of damage that we saw at the hospital last night.”

The IDF spokesman, Rear Admiral Daniel Hagari, was asked about this during Wednesday morning’s news conference – and said the scale of the destruction was caused by a misfired rocket from PIJ landing in a car park, and cars subsequently exploding.

Why were there so many people at the hospital?

Hundreds of Palestinians had taken refuge in al Ahli and other hospitals in Gaza City after Israel ordered all residents in the north to evacuate to the southern Gaza Strip.

Ibrahim al Naqa, a doctor at the hospital, told Reuters: “This place created a safe haven for women and children,
those who escaped the Israeli bombing.”