Four children were killed and two more wounded when a mortar shell fired by the Iran-backed Houthis on Saturday struck a residential area in the city of Taiz, in southern Yemen, residents said.

The six children, belonging to the same family, were playing in front of their house when the shell exploded, Ahmed Mansour, a local medic, told Arab News by telephone.

Residents said the targeted area is not close to the battlefields or military bases under the government’s control, adding that the shell was fired from a Houthi-controlled base east of Taiz.

The shelling is the latest in a series of deadly strikes by the Houthis on residential areas in Taiz that have killed dozens of civilians.

The attack came as local authorities in the central province of Marib announced that the death toll from the Houthi missile strike on the house of a tribal leader in Marib’s Juba district on Thursday evening had risen to 13 civilians. The bodies of seven unidentified civilians have been retrieved from the debris of the house.

The tribal leader, Abdul Latif Al-Qibli Namran, who survived the attack, vowed to fight off the Houthi attacks in Marib province till they are defeated. “We will fight as long as we breathe till victory is achieved,” he said.

Yemen’s Prime Minister Maeen Abdul Malik Saeed, who called Namran to offer his condolences, strongly condemned the Houthi attacks and vowed to make the Houthi militia “pay the price for crimes against civilians and the displaced,” the official news agency SABA said.

Juba has a large concentration of internally displaced people who fled fighting or Houthi repression.

As fighting between the government troops and the Houthis intensified in the district, local aid organizations and officials warned of a big humanitarian crisis as a large number of families are trapped with limited humanitarian assistance.

Local officials said on Saturday that the Houthi had intensified missile and mortar strikes on government-controlled areas in Juba to pave the way for their ground forces to advance.

Separately, the US special envoy for Yemen, Timothy Lenderking, on Saturday accused the Houthi of obstructing peace efforts to end the war and fueling the humanitarian crisis.

“Houthi escalation in Marib is not just an obstacle to peace, it is exacerbating a humanitarian situation already on the brink,” Lenderking said while discussing humanitarian crisis in Yemen with NGOs, according to the US State Department’s Bureau of Near Eastern Affairs.