Haitian rebels forced police out of another northern town and blocked a main road leading to the Dominican Republic (search), witnesses said Saturday as aid workers warned food was running out in northern cities and towns.

In Washington, members of the Organization of American States called on all parties to ensure a peaceful and democratic outcome to the 9-day-old rebellion aimed at ousting President Jean-Bertrand Aristide (search). About 50 people have died in the uprising.

Emergency supplies of flour, cooking oil, and other staples are projected to run out in four days in northern areas cut off by roadblocks guarded by rebels. The insurgents have seized Gonaives, Haiti's fourth-largest city, and burned down police stations in a dozen other towns.

Overnight, rebels attacked police in Saint Suzanne, a small town 20 miles southwest of the northern port of Cap-Haitien, according to witnesses reached by telephone.

They said police fled and rebels set the police station ablaze, but no one was killed.

Nearby, rebels blocked the road outside Trou-du-Nord that leads to the Dominican border at Ouanaminthe. Merchants turned back Saturday said the barricade of boulders and burned-out cars has cut supplies of food and fuel that come from Dominican Republic, which shares the island of Hispaniola (search) with Haiti.

Haiti has only 5,000 police officers and those manning outlying towns often are outnumbered and outgunned by insurgents.

"The population that is cut off completely from other parts of the country is finding itself in a very risky, very dangerous situation," Prime Minister Yvon Neptune told reporters in Port-au-Prince (search), the capital.

Leaders of the political opposition planned a rally in Port-au-Prince on Sunday, two days after Aristide militants crushed a planned demonstration by stoning opponents and blocking the protest route.

U.S. Secretary of State Colin Powell said Friday that Aristide's assurances he would work for a political settlement are not enough. Aristide "must reach out to the opposition, to make sure that thugs are not allowed to break up peaceful demonstrations," Powell said.

Powell met with OAS members in Washington on Friday and said they agreed "we will accept no outcome that, in any way, attempts to remove the elected president of Haiti."

The United States sent 20,000 troops to Haiti in 1994 to restore Aristide, end a bloody military dictatorship and halt an exodus of refugees to Florida.

Washington says it plans no new military intervention in the Caribbean country, where discontent has grown among the 8 million people since Aristide's party swept flawed legislative elections in 2000 and international donors froze millions of dollars in aid.

Opposition politicians refuse to participate in new elections unless Aristide steps down, and the rebels say they will lay down their weapons only when he is ousted.

Many who once backed Aristide have turned on him as poverty deepens while the president's clique enjoys lavish lifestyles some charge are funded by corruption.

In Gonaives (search), rebels lit flaming tire barricades early Saturday and patrolled with rifles amid rumors police plan to counterattack.

At the Gonaives hospital, more than a dozen people waited to see doctors who never came. Only one man remained in the hospital Friday, lying unattended in bed.

Pierre Joseph, a janitor, said doctors were afraid to return following a gunbattle a week ago, when police trying to retake the city stormed in carrying a wounded officer.

With rebels in pursuit, police opened fire inside the hospital, killing at least three civilian bystanders who were trying to hide, he said.

Rebels dragged a wounded officer from the hospital and stoned him to death, smashing in his head, according to a photographer. Police had tried to retake the city, but failed in what Neptune said was a "strategic retreat" to avoid killing civilians.

In the western city of St. Marc, where police have regained control from rebels, anti-Aristide militants burned down a clinic on Wednesday because officials refused to hand over two wounded colleagues.

Schools and many shops remain closed in Gonaives. A single bank reopened Friday, while dozens stood outside another desperate for cash transfers from relatives overseas that are the sole source of income for many.

Gas prices have more than doubled, with fuel coming in small bottles brought by motorcycle couriers.

In Port-au-Prince, U.N. representative Adama Guindo appealed to police and rebels to open a "humanitarian corridor" to northern Haiti.

Barricades have prevented the U.N. World Food Program from delivering food to some 268,000 people dependent on such aid in northern Haiti.

A barge of gasoline was on the way to Cap-Haitien, which has been without gas and power for days, and aid officials were negotiating to get 1,000 pounds of rice delivered by boat.