SANAA, Yemen (AP) — Shiite rebels who have seized control of Yemen's capital have violently dispersed demonstrations called to denounce the rebels' power grab. Witnesses say the rebels, known as Houthis, attacked and detained demonstrators Friday during nationwide rallies attended by tens of thousands. Among those arrested was the leader of the Sanaa University Student Union. Authorities could provide no detail on casualties. Houthis activists seized control of Sanaa in September and placed the president under house arrest, triggering his resignation and creating a vacuum of authority. Yemeni political parties are continuing talks with the United Nations envoy to Yemen, Jamal Benomar, over the possible formation of a presidential council to lead the country following the Jan. 22 resignation of President Abed Rabbo Mansour Hadi and his Cabinet.