AP – Tens of thousands of demonstrators, some chanting “down, down with the regime,” marched Thursday in several towns and cities in Yemen against the country’s autocratic president, a key U.S. ally in the fight against Islamic militants.

Police opened fire and used tear gas to break up one of the marches, witnesses said, and security officials confirmed a demonstrator was critically wounded by police fire. Two others were also hurt in the eastern town of Mukalla, but further details were not immediately available.