Rebel leader Mr Guy Philippe said this evening he will hold off attacking Haiti's capital for a day or two in response to appeals by the United States.
But rebel forces would continue to converge near Port-au-Prince in the meantime, he said from his base in Cap-Haitien, the second-largest city that fell last Sunday.
As Mr Philippe spoke his forces were within 25 miles of the capital where militants loyal to President Jean-Bertrand Aristide torched barricades, hijacked cars and looted the city's only operating hospital.
Mr Aristide has refused to step down, even as the United States urged him to give up power in the Caribbean nation.
Around 2,200 US marines were put on alert as Pentagon officials weighed up the possibility of sending troops to waters off Haiti to guard against a any flood of refugees and to protect the estimated 20,000 Americans in the country.
Meanwhile bands of armed Aristide loyalists roamed in trucks and cars through the chaotic capital. A body was seen at a roadside near the Cite Soleil slum, apparently hacked with machetes, and two more were found near the airport, one with hands bound.
Crowds of armed men, many wearing masks, blocked dozens of intersections, igniting piles of tires and harassing motorists. Gunfire rang through the sprawling city.
The stage was set for a showdown between the ragtag band of former soldiers and gang members trying to unseat Mr Aristide, and the diminutive former priest and one-time populist hero of Haitian democracy backed by an ill-trained, 4,000-member police force and armed supporters from the slums.
Mr Aristide, whom political opponents have long accused of corruption and political thuggery, again vowed he would not be pushed from office and appealed for help from foreign nations.
In Washington, US defense officials said they were considering sending a three-ship group carrying US Marines to Haiti to help deal with the crisis in the Caribbean country of eight million, the poorest nation in the Americas.
US President George W. Bush, asked if Mr Aristide should resign, pointed to comments from Secretary of State Mr Colin Powell on Thursday that Mr Aristide should "examine his position carefully," indicating US support for him was wavering.
The US Embassy in Port-au-Prince issued a statement late last night saying pro-government groups had begun to "burn, pillage and kill" and calling on Mr Aristide to put a halt to it.
"The armed gangs that are spreading terror and attacking civilians ... are acting in the name of Jean-Bertrand Aristide," said the statement, which also called on the rebels to halt their advance on the capital.
UN Secretary-General Mr Kofi Annan was "increasingly concerned" at the deteriorating situation in Haiti and called for a peaceful solution, his spokesman said in a statement.
He warned leaders would be held "accountable for any breaches of international human rights and humanitarian law."
Rebel leader Mr Guy Philippe, a former police chief accused of plotting coups who returned from exile in the Dominican Republic to join the three-week-old revolt, said his men planned to cut off Port-au-Prince from the ocean.