A Saudi-led Arab military coalition said Friday that it would investigate an airstrike in Yemen that killed at least 50 people, many of them children, after earlier defending the attack and calling it a "legitimate military action."
The shift came as the attack drew wide international criticism, including a U.N. Security Council call for an independent investigation of the airstrike.
Yemen's Houthi rebels said at least 40 children were killed in Thursday's strike in the north of the country, with one of the missiles hitting a bus bringing children back from a summer school picnic. Rebels said the strike also wounded at least 77 people.
A spokesperson for the Saudi Embassy in Washington, Fatimah Baeshen, said in a statement that the case had been referred to the coalition's investigative body.
"The coalition will, as it has always, exert all efforts to preserve civilian lives,'' she said.
The coalition initially said the airstrike was a "legitimate military action" and accused Houthis of recruiting children and using them in the battlefields as cover.
The Security Council called for a credible and transparent investigation of the strike.
Britain's U.N. Ambassador Karen Pierce, the current council president, told reporters: "The important thing is the word 'credible.' If there's an acceptable, credible investigation, then the council will want to consider next steps in the light of that.''
U.N. Secretary-General Antonio Guterres also urged an "independent and prompt investigation" of the airstrike.
Mohammed Ali, a senior Houthi leader, said on Twitter that the Houthis welcomed Guterres' call for a probe and were "ready to cooperate."
The U.S. State Department called on the coalition "to conduct a thorough and transparent investigation into the incident.'' State Department spokeswoman Heather Nauert said, "We take all credible accounts of civilian casualties very seriously."
UNICEF chief Henrietta Fore said in a statement Friday that the "horrific" attack "marks a low point" in Yemen's brutal war. "The question now is whether it will be a turning point — the moment that must finally push the warring parties, U.N. Security Council and international community to do what is right for children and bring an end to this conflict."
Television pictures from a Yemeni hospital showed blood-covered youngsters who seemed too stunned to even cry. Others writhed on the floor, waiting for help.
The medical charity Doctors Without Borders said "civilians continue to pay the highest price" in Yemen.
Thursday's airstrike was carried out against a rebel-held area in Saada province, near the Saudi border. Missiles struck a market.
It came in response to a Houthi missile strike on Saudi territory Wednesday. Saudi defenses intercepted the missile, but fragments fell to the ground, killing one and wounding 11.
Iranian-backed Houthi rebels seized the Yemeni capital of Sanaa in 2014, sending the Western-supported government into exile in Saudi Arabia.
The coalition began its air and ground campaign to drive out the Houthis more than three years ago. Its airstrikes have obliterated entire civilian neighborhoods, including schools and hospitals, and compounded the misery of what is one of the world's worst humanitarian disasters.
Many Yemenis are in the brink of starvation. There are also severe shortages of fresh water and medicine. A cholera epidemic has killed thousands over the last two years.