Haitian President Jean-Bertrand Aristide has fled the country, and the country's Supreme Court chief justice has assumed leadership.
In a news conference Sunday, Boniface Alexandre said he is taking office in accordance with the constitution. He also appealed for calm in the country, where rebels have waged a violent three-week revolt to force Mr. Aristide's ouster.
As Mr. Alexandre spoke, the American ambassador to Haiti, James Foley, announced that U.S. troops will deploy rapidly to restore order in the Caribbean island country.
Mr. Aristide bowed to increasing international pressure and flew out of the country early Sunday. His prime minister, Yvon Neptune, says a letter of resignation was signed before Mr. Aristide's departure.
Early reports say he would stopover in the neighboring Dominican Republic, before seeking asylum in either Morocco, Taiwan or Panama.
The developments come as hundreds of armed militants loyal to Mr. Aristide protest outside the national palace in the capital, Port-au-Prince. Several large fires are also raging throughout the city.
Senior U.S. officials quickly welcomed the news of Mr. Aristide's departure, which followed growing pressure from the United States, France and several other nations.
As recently as Saturday, Mr. Aristide, a former Roman Catholic priest, said his resignation was "out of the question." He was the Caribbean island nation's first freely elected president in 200 years of independence.
The crisis in Haiti has been brewing since Mr. Aristide's party swept legislative elections in 2000 that were widely dismissed as flawed, and international donors froze millions of dollars in aid.
The United States sent 20,000 troops to Haiti to restore Mr. Aristide to power after he was ousted by a coup 10 years ago, but on Saturday the White House blamed him for the current political crisis.
Violence in Port-au-Prince eased since Saturday, but sporadic gunfire was still heard early today, and looting continued at the city's port facility.