Yemeni security officials say gunmen shot dead a pro-government army colonel in the southwestern city of Taiz.
They say Colonel Radwan el-Wassabi, who was backed by the United Arab Emirates, was shot dead and at least four of his guards were wounded late on Saturday in central Taiz.
The city is split between government and rebel control. It was unclear who was behind the shooting.
A Saudi-led coalition has been at war with Yemen's Shi'ite Houthi rebels since March 2015. The rebels control much of northern Yemen, including the capital, Sanaa.
Tensions have risen in recent months between Yemen's internationally recognised government and the United Arab Emirates. Clashes have occasionally broken out between the two coalition allies.
The officials spoke on condition of anonymity because they weren't authorised to brief media.