The rebels, known as Houthis, took Aden's southwestern Tawahi district, killing the area's military commander, Maj. Gen. Ali Nasser al-Hassani, in the process and seizing the palace, military officials said.
US forces once used the palace, which overlooks the city's port entrance, as an operations center and training facility for anti-terrorism forces after rebels captured the capital last September, they said. Experts and trainers left this spring when clashes began in Aden.
Meanwhile, security officials say Saudi-led airstrikes continued to pound the rebels, striking targets in Aden as well as the cities of Marib, Saada and Dhamar. Dozens of rebels and their allies were killed there, they said.
There also was fighting today in Marib province, and aircraft also struck the Anad air base north of Aden, once a site of US intelligence operations.