The funeral was held in the family compound of the assassinated president, Jovenel Moïse, just outside the northern city of Cap-Haïtien, with grandstands erected inside an arena around a central stage, dressed with white curtains and flowers, where his coffin was set, covered in a Haitian flag and guarded by four men in military uniforms.

Though the setting was serene, the tensions that had rocked the streets the afternoon before leaked quickly into the ceremony.

A line of Mr. Moïse’s supporters stood by the entrance to the funeral and yelled at arriving politicians: “Justice for Jovenel!”

When Haiti’s national police chief, Leon Charles, arrived, the crowd surged around him and erupted into shouting and finger pointing. As he passed the grandstand of invited guests, many there also jumped to their feet to shout their displeasure.

“He killed the president!” yelled Marie Michelle Nelcifor, adding she believed Mr. Moïse had telephoned Mr. Charles while assassins attacked his home but that Mr. Charles had not sent police officers to defend him. “Where were the security guards?” she asked.

Others were angry that the investigation into his assassination had not been completed. “They are burying him surrounded by his assassins!” shouted Kettie Compere, a mother of two looking up at the grandstand of diplomats and Haitian politicians where Mr. Charles had settled.

When Martine Moïse, the president’s widow, arrived dressed in black with a large black hat and a mask with a photo of her husband affixed to it, the crowd surged around her, singing “arrest them, arrest them.”

Speaking publicly for the first time since the assassination, which also left her wounded, Ms. Moïse delivered a eulogy that was pointedly political. While telling the mourners that her family is “living in dark days,” she also implied that her husband had been killed by the country’s leading bourgeoise families.

“Is it a crime to want to free the state from the clutches of the corrupt oligarchs?” she said, standing at the podium with her three children surrounding her.

“The raptors are still running the streets with their bloody claws,” she said. “They are still looking for prey. The are not even hiding. They are there watching me and listening to us, hoping to scare me. Their thirst for blood has not been quenched yet.”

The smell of tear gas wafted over the family compound during the funeral.

Following the ceremony, Cap-Haïtien seemed to descend into lawlessness. The main roads of the city were clogged with burning tires and barricades made from boulders and wood. Roaming packs of men, some masked and armed, stopped motorcyclists and robbed them.

At least one home appliance store was looted, with people carrying away refrigerators and air conditioners. All the businesses along the downtown streets were shuttered.

The American delegation that arrived in the city earlier Friday said its objective was to re-engage with Haiti and help the country overcome a litany of problems compounded by Mr. Moïse’s assassination.

“You deserve democracy, stability, security and prosperity, and we stand with you in this time of crisis,” Ms. Thomas-Greenfield said.

In an interview, a member of the delegation, Juan Gonzalez, President Biden’s top adviser on Latin America, said it wanted to promote cooperation among political factions in Haiti. He also said the White House believed Haiti should proceed with elections, but only when safe to do so.

The White House national security adviser, Jake Sullivan, said after the delegation flew home that the United States remained “deeply concerned” about Haiti.

“We strongly urge all parties to express themselves peacefully, and call on Haiti’s leaders to be clear that their supporters must refrain from violence,” Mr. Sullivan said in a statement. The delegation, he said, had “met with senior Haitian officials and civil society leaders and shared this message directly.”

The July 7 killing of Mr. Moïse, 53, in the bedroom of his home near Port-au-Prince, the capital, has plunged the Caribbean nation of 11 million into a deep crisis. Officials have blamed a group of Colombian mercenaries, but many questions remain unanswered, including who planned the assassination and why no members of the president’s security detail were hurt. Several members of that security detail have been questioned and taken into custody.

Pressured by Western countries led by the United States, Haiti’s other political leaders, jostling for power, have pledged an orderly transition and a democratic process. A new government was installed in the capital this week, and its leaders vowed to get to the bottom of the assassination and to build consensus among the country’s political factions and civic groups.

But it was clear even before the funeral that deep divisions would shape and possibly subvert what many hoped would be a venue for reconciliation.

The night before, Cap-Haïtien burned with anger and frustration, exposing deep divisions in Haitian society that have existed since the former French colony of slaves rebelled and defeated Napoleon’s troops.

The streets billowed with the black smoke of burning tires, a common form of protest in a country split by geography, wealth and power. Large crowds of demonstrators ran through the narrow colonial streets, chanting, “They killed Jovenel, and the police were there!”

Angry men tried to block the arrival of mourners from the country’s south, throwing a concrete block at the lead car of a motorcade that had navigated through fire, and later dragging a concrete telephone pole across a road.

“We sent them someone alive, they sent him back a cadaver,” screamed Frantz Atole, a 42-year-old mechanic, promising violence. “This country is not going to be silent.”

The disdain for the country’s economic elite, expressed by Ms. Moïse in her eulogy, was clearly a prevailing emotion among the protesters on Thursday.

“The bourgeoisie from Port-au-Prince are responsible. They are the reason for all of this,” said Emmanuella Joseph, a 20-year-old secondary school student, crying into a face cloth on the side of the road at the tail end of a running protest.

She added that the president’s killers were outsiders who had long meddled with the country’s destiny. “What kind of nation comes and kills a president?”

Cap-Haïtien was once the capital of the French colony of St. Domingue, which claimed one of the most brutal slave plantation economies in the world and was later overwhelmed by the world’s most successful slave rebellion. Banners strung across its roads read “Justice for President Jovenel” and “Thank you President Jovenel. You gave your life for the people’s fight and it will continue.”

Just off the city’s main stone square, where rebel leaders were executed more than two centuries ago, mourners lined up on Thursday to sign condolence books and light candles before a large photo of the president in a government building.

“We are living in a time that’s so fragile,” said Maxil Mompremier, standing outside the colonial-era Notre Dame de L’Assomption Cathedral, where Mr. Moïse’s supporters had gathered earlier for a service. “Nobody understands what happened. A lot of people are afraid.”