Updated

Yemeni security officials and witnesses say Shiite Houthi rebels fired mortars and rockets into the central city of Taiz, killing at least 15 civilians and wounding seven.

Taiz, Yemen's third-largest city, is besieged by the rebels. Witnesses, who spoke on condition of anonymity for fear of retribution, say the shells landed in residential areas on Wednesday.

The officials, who are neutral in a conflict that has split the armed forces, say Saudi-led warplanes struck Houthi positions and clashes raged on the outskirts of Taiz. They spoke on condition of anonymity because they were not authorized to brief the media.

Yemen's fighting pits the Houthis and allied army units against forces loyal to the coalition-backed government as well as southern separatists and other militants. The Saudi-led air campaign began in March.