Shortly after Powell entered the National Palace in the Haitian capital for meetings with President Boniface Alexandre and Prime Minister Gerald Latortue, gunfire erupted outside. It was not clear whether the shots were aimed at the palace, but a palace security officer said they appeared to come from a single passing car.
U.N. security forces guarding the palace returned fire with automatic weapons. Shortly thereafter, several U.N. tanks arrived to patrol the road in front of the palace.
Besides Alexandre and Latortue, Powell was seeing leaders from various civil and political groups in Haiti, most of whom opposed Aristide, who was ousted in February with the help of the Bush administration.
Powell in particular was instrumental in the removal of Aristide and installation of a caretaker government that promised a rapid return to true democratic rule. The one-year anniversary of Aristide's ouster is approaching in February.
Powell went to Haiti to reaffirm U.S. support for democracy there, review American efforts to help the country overcome recent natural disasters, and commemorate World AIDS Day by meeting with young Haitians who receive and provide HIV/AIDS support services.
State Department spokesman Richard Boucher said the United States was making available $46 million to help Haiti overcome damage from recent flooding and hurricanes.
It also pledged $230 million at a Haiti donors' conference to assist Haitians in job creation, budget support and other areas, Boucher said.
In the fiscal year that ended in September, the United States committed $20 million to Haiti to support a treatment, care and prevention program for HIV/AIDS. About 5 percent of the population of 8 million is estimated to be infected with HIV/AIDS, the highest rate in the Western Hemisphere.
Powell announced last month that he would leave his post in President Bush's second term. Bush has nominated White House national security adviser Condoleezza Rice to succeed Powell.
Latortue was placed in charge of the interim Haitian government after bands of rebels and former soldiers launched a three-week rebellion in February that ended with Aristide's ouster and the arrival of a U.S.-led peacekeeping force.
Latortue has promised to hold free elections next year, but Aristide's followers and some outside relief and religious groups doubt his sincerity.
The trip was Powell's second to Haiti in eight months. He also visited in April, five weeks after Aristide fled the country amid charges by Aristide and others that the Bush administration coerced him to leave.
Aristide's followers say Powell signed off on a plan to remove Aristide because he was seen as a troublemaker whose unpopularity could destabilize Haiti and cause a tide of refugees heading for U.S. shores.
The administration says Aristide departed voluntarily.
Despite the presence of peacekeeping troops, now under the aegis of the United Nations, the rebels and former soldiers have refused to abandon police stations across the country. They have also refused to disarm, saying they need to stabilize Haiti until the government reinstates the military and the police hire more recruits.
The U.S.-backed interim government has accused Aristide of orchestrating recent political violence from exile in South Africa. Aristide has denied supporting violence.
At least 89 people have been killed in politically linked violence since Sept. 30, when pro-Aristide groups stepped up protests demanding his return.
Haiti is the Western Hemisphere's poorest country and most residents get by on less than $1 a day.
On Monday, the U.N. Security Council condemned "all acts of violence and the attempts by some armed groups to perform unauthorized law enforcement functions in the country."
It also voted unanimously to keep U.N. peacekeepers in Haiti for six months.
The State Department on Tuesday said there were approximately 4,800 U.N. troops and 1,270 U.N. civilian police in Haiti. Three U.S. military personnel and one U.S. Coast Guard official were participating.