An attack on a bus carrying children in rebel-held northern Yemen on Thursday left dozens of people dead or wounded, the International Committee of the Red Cross said.
"Following an attack this morning on a bus driving children in Dahyan Market, northern Saada, (an ICRC-supported) hospital has received dozens of dead and wounded," the organisation said on Twitter without giving more details.
"Under international humanitarian law, civilians must be protected during conflict," it added.
The Houthi rebels' Al Masirah TV reported that 39 people had been killed and 51 wounded, "mostly children".
It accused the Saudi-led coalition fighting the Shia rebels on the side of the government of hitting the bus in an air strike.
It was not possible to verify the toll or who was behind it.
There was no immediate comment from the coalition, which intervened in 2015 to try to restore the internationally recognised government to power after it was driven out of the capital Sanaa by the rebels.
Yemen's war has left nearly 10,000 people dead and unleashed what the United Nations describes as the world's worst humanitarian crisis.