At least four dozen civilians - many of them children - have been killed in an air strike in Yemen. Scores more were injured. The Saudi-led coalition fighting Houthi rebels says it was justified in carrying out the attack - while humanitarian groups are crying foul. CGTN's John Metherell has more.

The images of the wounded heart-rending: Children, battered and bloodied. Dozens of others, killed. Their school bus, collateral damage - in a Saudi coalition strike against Shiite Houthi targets in Yemen's civil war.

AHMED MOHAMED AL ATWANY HEAD OF EMERGENCY DEPARTMENT, SAADA HOSPITAL "The number of dead and injured is quite high, among them elderly and children."

The attack took place in the Dahyan market in Saada province, a Houthi stronghold. The Saudi-led coalition said it launched the attack in retaliation for a missile Wednesday in the country's south - and called it a "legitimate military action".

A coalition spokesman also accused Houthis of using children as covers for their acts. The charity group, Save the Children, described the incident as "horrific" and called for an independent investigation into civilian attacks in Yemen. Later on Thursday, air strikes hit Sanaa. The U.N. special envoy for Yemen, Martin Griffiths, has been pushing to bring the warring parties to restart peace talks to end the three-year civil war. John Metherell, CGTN.