At least four people have been shot and wounded as supporters of Haitian President Jean-Bertrand Aristide reacted to a huge anti-Aristide march with their own demonstrations in the capital.
Gunshots were heard overnight in various Port-au-Prince neighbourhoods as Aristide supporters fired into the air, burned tires and set up barricades at intersections, seeking to take back the streets after Thursday's march by thousands of students.
Witnesses said at least four people were shot and wounded, one of them with a bullet to the head, in two neighbourhoods of the city during Friday's unrest. It was not clear whether they were government supporters or opponents, or who shot them.
State offices, international organisations, private schools, gas stations and other businesses in the city were closed, fearful of violence.
In Washington, the State Department said the U.S. embassy had been closed due to the unrest and it warned Americans against travelling to Haiti.
State Department spokesman Lou Fintor said tension was also high in Gonaives, Cap Haitien, Petit Goave and Jacmel.
"Some international organisations have decided to draw down their staffs in Haiti," Finto said.
He said the Haitian government had not been able to keep order in the capital and "in some instances has assisted in violently repressing the demonstrations".
On Thursday, thousands of students and others took to the streets to call for Aristide's resignation, blaming him for violence against protesters in past demonstrations. It was one of the largest political demonstrations in Haiti this year.
Several hundred supporters of the president gathered in front of the National Palace on Friday morning and marched around the block, beating drums and singing.
Some chanted, "Cut off heads, burn down houses," a battle cry of the father of Haiti's independence, Jean-Jacques Dessalines, who led the Caribbean country to independence from France in 1804.
Some demonstrators carried saws or swords and called out threats to students and journalists.
Several hundred students and other opponents of the president marched in Port-au-Prince and nearby Petion-Ville, where they were occasionally tear-gassed by riot police.
After Thursday's demonstration, Aristide supporters fired guns and threw rocks at the offices of two independent radio stations, Caraibes and Kiskaya. A third station, Radio Metropole, received threats and shut down its news service early.