Houthi fighters opposed to Yemen's president took over the central city of Taiz in an escalation of a power struggle diplomats say risks drawing in neighboring oil giant Saudi Arabia and its main regional rival Iran. Residents of Taiz, on a main road from the capital Sanaa to the country's second city of Aden, said that Houthi militias took over the city's military airport without a struggle from local authorities late on Saturday. Eyewitnesses in the central province of Ibb reported seeing dozens of tanks and military vehicles headed southward from Houthi-controlled areas toward Taiz, while activists in the city said Houthi gunmen shot into the air to disperse protests by residents demonstrating against their presence. Conflict has been spreading across Yemen since last year when the Houthis seized the capital Sanaa and effectively removed President Abd-Rabbu Mansour Hadi, who now seeks a comeback from his base in Aden. The advance of the Iranian-backed group has angered Sunni Gulf Arab states led by Saudi Arabia. The Houthi spread into mostly Sunni areas in the center and west have led to months of clashes with local tribes and al Qaeda, raising fears that the poor and heavily armed country at the base of the Arabian peninsula might descend into civil war.