After 24 hours of wild gunbattles with suspects in the assassination of Haiti’s president, the nation’s authorities announced the arrests of 20 people and called on the United States to send troops to help protect crucial infrastructure.

Haiti’s remarkable request for military assistance from the United States, a former colonial overlord that has repeatedly intervened in the island’s affairs, is a measure of how deeply shaken the nation has been by days of chaos and intrigue. As new developments unfolded at a dizzying pace today, the mystery over who was ultimately behind the assassination only deepened.

On the streets, vigilantes prowled for suspects, and the police killed at least three people in gunfights. The vast majority of those arrested have turned out to be from Colombia — former military men turned mercenaries — as questions arose about why it had been so easy for attackers to burst into President Jovenel Moïse’s home and kill him, seemingly with no shots fired from security staff.

And in a brewing political crisis, suspicion has prompted what may shape up to be a standoff between rival governments.

Of the 20 people detained by the police, 18 were identified as Colombians, and two as Americans of Haitian descent, with five more suspects said to be on the loose.

Officials in Colombia said that at least 13 of the men used to be in the Colombian military, and that two of them had been killed. The two Americans arrested said in an interview with a Haitian judge that they were not in the room when Moïse was killed and that they had worked only as interpreters for the hit squad. One said he had answered an internet ad for the job.

The Haitian authorities summoned four of the president’s security figures for questioning next week, as prosecutors sought to unravel exactly how armed assassins could have breached the complex security operation guarding Moïse’s personal residence without encountering much resistance.

But while Haitian officials have pointed to “foreign involvement,” U.S. officials and many observers within Haiti are increasingly questioning whether the attack was planned with the cooperation of the nation’s own security apparatus. The State Department told lawmakers recently that there were no reports that the attackers injured any guards or even exchanged gunfire with them.

“The group that financed the mercenaries want to create chaos in the country,” said Mathias Pierre, Haiti’s minister in charge of elections, who said that the Haitian government had requested American forces to help protect the country’s airport, port and fuel reserves, among other crucial infrastructure.

“Attacking the gas reserves and airport might be part of the plan,” Pierre said.

The Haitian ambassador to the United States also requested assistance from the FBI in the investigation of the assassination.

In Washington, a senior Biden administration official said that FBI and Department of Homeland Security officials would go to Port-au-Prince “as soon as possible” to assess how to help. The official also said, “There are no plans to provide U.S. military assistance at this time.”

Haiti lurched closer toward an outright internal power struggle today when political parties directly challenged the sitting prime minister by declaring that they wanted to form a government to replace him, headed by the Senate president — one of just 10 sitting elected parliamentarians in the country. Another group of civilian activists was planning a large meeting on Saturday to build a consensus on how to move the country forward.

Sen. Patrice Dumont accused the interim prime minister, Claude Joseph, of staging a coup d’état: “He wasn’t a normal prime minister, and he installed himself — we cannot accept this,” he said on the local radio station, Kiskeya.

The tumult now gripping Haiti has only sharpened the internal tensions that have been building in recent months. Gang activity has ramped up, with brazen kidnappings and armed attacks on poor neighborhoods of the capital sending thousands fleeing from their homes. At one point last month, gangs shut down the main arterial road from the capital to the country’s south, blocking off access to both the petroleum reserves and the rest of the country, Pierre pointed out.

In the absence of clear information about who was responsible, some Haitians tried to take justice into their own hands, burning cars they thought might have been used in the attack and rounding up people they believed to be suspects.

After several gunfights with the police, at least three men were killed. Two of their bodies, struck by bullets, were recovered on the main road leading into the president’s neighborhood and a third was found dead on the roof of a private residence in an area of Pétionville, a suburb of the capital.

On Thursday morning, security personnel at the Taiwanese Embassy discovered a group of “fully armed, suspicious-looking individuals” trying to break into the compound, said Joanne Ou, a spokeswoman for Taiwan’s foreign ministry. Haitian police arrested the 11 “mercenaries,” according to a statement today released by the embassy, though it wasn’t immediately clear how they were connected to the attack.

Clément Noël, a judge who is involved with the investigation, said he had interviewed both American men soon after their arrest. He identified them as James J. Solages, a U.S. citizen who lived in South Florida and previously worked as a security guard at the Canadian Embassy in Haiti; and Joseph Vincent, 55. The U.S. government has been in touch with Solages, according to two people who have been in contact with the State Department and spoke on the condition of anonymity.

Noël, speaking by telephone, said the two Americans maintained that the plot had been planned intensively for a month. He said that the Americans had met with other members of the squad at an upscale hotel in Pétionville to plan the attack. He said they had relayed that the goal was not to kill the president but to bring him to the national palace.

Noël said that Solages told him that at the beginning of the assault, he yelled over a loudspeaker that the attackers were agents of the U.S. Drug Enforcement Agency.

Vincent said he had been in the country for six months and that he had been staying with a cousin. Solages said he had been in Haiti for a month. The men said the Colombians involved in the plot had been in the country for about three months.

All that Vincent would say about the broader plot was that the mastermind was a foreigner named “Mike” who spoke Spanish and English. Solages said that he had found the job to interpret for the hit squad in a listing posted online. They would not say how much they had been paid.

Noël said Solages had “replied in a very evasive manner.”

Today, officials in the Colombian defense ministry identified 13 of the accused participants in the Haiti attack by name, all of whom they said were former members of the Colombian military. Two had been killed, while the other 11 were in custody.

Gen. Jorge Luis Vargas, the head of the Colombian national police, said that officials were investigating four businesses that they believed had recruited individuals for the operation, and they were using the businesses’ Colombian tax numbers to learn more.

At least one of the detained men, Francisco Eladio Uribe, was being investigated last year by the country’s special peace court for homicide, according to documents obtained by The New York Times. Uribe was accused of being involved in the country’s “false positives” scandal, in which hundreds of members of the military have been accused of killing civilians and presenting the victims as combat casualties in a bid to show the country was winning its long civil war.

In an interview with a local radio station, a woman who identified herself as Uribe’s wife said the two had been married 18 years and had three children, and that he had left home one day after he told her that he had “a very good job opportunity.” She said her husband had been investigated in the false positives case, but had been exonerated.

Colombian officials said that some of the accused individuals left Bogotá as early as May, and flew to Panama before traveling to the Dominican Republic and then to Haiti. Others arrived in the Dominican Republican in early June, and then traveled to Haiti.

Colombia has a large military that has spent decades fighting left-wing guerrilla groups, paramilitaries and drug traffickers, often with U.S. funds and training. Over the years, thousands of young Colombian men have been conscripted into the military, but they often leave service with limited professional options.

This has made them attractive to people looking for hired guns. By 2015, for example, the United Arab Emirates had secretly dispatched hundreds of Colombians to Yemen to fight in the country’s violent civil conflict. Many stayed because of the high pay, according to past New York Times reporting, with the Colombians receiving salaries of up to $3,000 a month, compared with about $400 a month they would make at home.

“When an economic underclass is taught how to fight and how to conduct military operations and little else, those skills don’t transfer readily to the civilian sector except in the private security realm,” said Paul Angelo, a fellow at the Council on Foreign Relations who studies security issues.

Today, Gen. Luis Fernando Navarro, the commander of Colombia’s army, said that the accused individuals had left the military between 2002 and 2018. He said the men were involved in “mercenary activities,” and that their motives were “purely economic.”