Egypt agreed to reopen its border crossing with the Gaza Strip to allow aid to reach Palestinians, the U.S. said, as the humanitarian crisis worsened for the 2.3 million people trapped in the enclave and anti-Israel protests flared across the Middle East.

The region remained volatile in the aftermath of an explosion at Gaza's Al-Ahli al-Arabi hospital late on Tuesday, which Palestinian officials said killed 471 people and blamed on what they said was an Israeli air strike.

Israel and the U.S. said the cause was a failed rocket launch by Islamist militants in Gaza who denied responsibility. Israel's Foreign Ministry spokesperson Lior Haiat said the death toll from the blast was only "several dozen."