A summit between between Palestinian, US, Jordanian and Egyptian leaders, has been cancelled, just hours before Joe Biden was due to visit the region.
The US president was set to meet them after his visit to Israel on Wednesday.
The summit’s cancellation is a blow to Mr Biden’s diplomatic efforts over the Middle East crisis.
Follow live: ‘Hundreds’ dead in hospital strike
Jordan’s foreign minister Ayman Safadi said: “There is no use in talking now about anything except stopping the war.”
Mr Biden will no longer visit Jordan, and instead only visit Israel, the White House said.
A spokesperson said: “After consulting with King Abdullah II of Jordan and in light of the days of mourning announced by President Abbas of the Palestinian Authority, President Biden will postpone his travel to Jordan and the planned meeting with these two leaders and President Sisi of Egypt.”
In a statement, President Biden said: “I am outraged and deeply saddened by the explosion at the Al Ahli Arab hospital in Gaza, and the terrible loss of life that resulted. Immediately upon hearing this news, I spoke with King Abdullah II of Jordan, and Prime Minister Netanyahu of Israel and have directed my national security team to continue gathering information about what exactly happened.
“The United States stands unequivocally for the protection of civilian life during conflict and we mourn the patients, medical staff and other innocents killed or wounded in this tragedy.”
Biden now has a 10-hour flight to work out his next steps
It is only a 20-minute drive from where I am at the White House to joint base Andrews where Air Force One was waiting on the tarmac to pick up President Biden.
But even in that short journey the president’s trip to Israel and the Middle East was plunged even further into crisis.
A planned summit with regional leaders in Jordan was already hanging by a thread after the president of the Palestinian Authority, Mahmoud Abbas, withdrew. But as President Biden’s motorcade zoomed towards the airstrip, King Abdullah of Jordan cancelled the meeting entirely.
It means one half of President Biden’s trip is now non-existent. He was going to use that meeting to urge those leaders to throw their support behind Israel as the US has, and attempt to stave off a wider conflict.
The complexion of his trip has completely shifted since the horror of the hospital blast in Gaza. President Biden now has a 10-hour plane journey to contemplate how to react to that given the competing narratives of who is responsible.
But who knows what might have happened by the time he lands in Tel Aviv?
The summit would have focused on getting humanitarian assistance into Gaza, while working towards calming tensions in the region.
The cancellation of the summit comes after a deadly strike on a hospital in Gaza, which the Hamas-led government said has killed up to 500 people.
Hamas has blamed Israel for the incident, while Israel said the Palestinian Islamic Jihad (PIJ) group was responsible.
King Abdullah II said the strike was a “shame on humanity”, and called on Israel to immediately stop its military campaign in Gaza.
Accusing Israel of the strike, leader of the Palestinian Authority Mahmoud Abbas said the country has crossed “all red lines” and described it as a “hideous war crime”.