How the Gaza hospital explosion set off a furious scramble before Biden's Israel trip

A deadly blast at a hospital in Gaza hours before President Joe Biden was set to leave the White House for the Middle East set off a furious scramble inside his administration as the president's advisers tried to ascertain who was responsible as street protests against Israel started raging across the Arab world.

Hours later, the president and his national security team were not confident enough to draw a final determination absolving Israel of responsibility. But the initial information they evaluated strongly suggested that the Israelis were not behind the strike, serving as a green light for Biden's motorcade to roll out to Joint Base Andrews late Tuesday afternoon, sources familiar with the internal deliberation told CNN.

Had the early evidence examined by the president's team pointed in the other direction, the White House would have been more inclined to reconsider the trip. But advisers were sensitive about reversing course mere hours after the trip was announced by Secretary of State Antony Blinken, and in the end, they never came close to canceling the trip altogether, sources said.

"He had no choice. Once he decided to do it, he wouldn't cancel it," one source said, describing what was understood to be an extraordinarily high bar for canceling Biden's visit, which only included a stop in Tel Aviv after Arab leaders canceled a planned summit with Biden in Amman, Jordan, in response to the hospital explosion.

The first public statement from the White House on the blast - which authorities in Hamas-run Gaza have said killed hundreds of civilians - condemned the civilian casualties and said the administration would continue studying the intelligence. En route to Israel on Air Force One, White House spokesman John Kirby would only go as far as to say, "We certainly recognize that they feel very strongly that - that this was not caused by them," when asked whether the US would give Israel "the benefit of the doubt."

Back at home, Biden's team worked through the night, delivering an initial intelligence assessment in the early morning hours Wednesday, according to a source familiar. The president was briefed on that assessment, leading him to be explicit about who was to blame for the hospital strike: "Based on the information we've seen to date, it appears the result of an errant rocket fired by a terrorist group in Gaza."

Officials told CNN separately that the initial evidence gathered by the US intelligence community suggests that the hospital strike came from a rocket launched by the Palestinian Islamic Jihad group and the National Security Council said in a statement on Wednesday that the US assesses that Israel was not responsible for the attack.