"Scores killed, even more, injured, most under the age of 10," Johannes Bruwer, head of the delegation for the ICRC in Yemen.

Saudi-led coalition air strikes killed dozens of people Thursday, including children traveling on a bus through a market, in Yemen's Saada province, a Yemeni health official said, and the International Committee of the Red Cross (ICRC) has confirmed.

The Western-backed alliance fighting the Iranian-aligned Houthi group in Yemen said in a statement that the air strikes targeted missile launchers used to attack the southern Saudi city of Jizan Wednesday, killing a Yemeni civilian there.

Houthi spokesman Mohammed Abdul-Salam said the coalition showed "clear disregard for civilian life" as the attack had targeted a crowded public place in the city.

The ICRC said a strike hit the bus driving children in the Dahyan market, in northern Saada.

"Our shops were open, and shoppers were walking around as usual. All of those who died were residents, children and shop owners," witness Moussa Abdullah, who was being treated in hospital for wounds, told Reuters.

The ICRC said on its Twitter account that its medical team at the ICRC-supported hospital in Saada had received the bodies of 29 children, all under 15 years old. The hospital also received 48 wounded people, among them 30 children.

That was the toll at just one hospital.

Abdul-Ghani Sareeh, from Saada health department, told Reuters: "A bus carrying children was targeted today while they were coming from summer school resulting in 43 martyrs and almost 63 wounded."

White plastic body bags filled the floor of a room in the ICRC-supported hospital.

Injured children, bloodied, bandaged and screaming, lay on stretchers as doctors treated them, friends and relatives have carried some of them in their arms to be treated.

"Scores killed, even more, injured, most under the age of 10," Johannes Bruwer, head of the delegation for the ICRC in Yemen, said earlier in a Twitter post.

It was unclear how many of the dead in total were children and how many air strikes were carried out in the area, in northern Yemen, near the border with Saudi Arabia.