Four people suspected of being involved in the assassination of Haitian President Jovenel Mose were killed by the police in an exchange of fire and two others were arrested, the Haiti police chief said on Wednesday. The chief, Léon Charles, also said three police officers who had been held hostage have been released.

“The police are fighting with the attackers,” he said at a press conference, noting that the authorities were still pursuing a few suspects. “We pursue them so that they meet their fate in a shootout or die in a shootout or we arrest them.”

Millions of Haitians anxiously huddled around radios and televisions all day, staying away from the streets to understand who killed the president, why and what the coming days could mean for the country. The attack created a political void that threatens to deepen the turmoil that has gripped Haiti for months.

Mr Moïse’s wife, Martine Moïse, was also shot dead in the attack, Interim Prime Minister Claude Joseph said in a statement. Ms. Moïse was taken to a hospital in South Florida for treatment.

“A group of strangers, some of whom speak Spanish, attacked the private residence of the President of the Republic, fatally injuring the head of state,” said the prime minister, but little confirmed information was available as to who might have carried out the assassination.

In an interview with the New York Times, Mr. Joseph said that he is the one ruling the country at the moment. However, it was unclear how much control he had or how long it would take. A new prime minister was slated for this week to replace Mr Joseph and the chairman of the nation’s highest court, who may also have helped restore order, died of Covid-19 in June.

Later on Wednesday, Mr. Joseph presented himself as head of government on a television broadcast to the nation, announcing that he and his fellow ministers had declared a “state of siege”.

Mr. Joseph called for calm.

“Let’s look for harmony in order to move forward together so that the country doesn’t get into chaos,” he said.

He also vowed that the commando that carried out the attack would be brought to justice.

News of the murder of Mr Moïse rocked the Caribbean nation 675 miles southeast of Miami. But it was already in turmoil.

Protesters have taken to the streets in recent months to demand that Mr Moïse be removed. He had clung to power and ruled by decree for over a year, although many – including constitutional scholars and legal experts – argued that his term had expired. Others, including the United States, supported his position that his term does not end until next year.

Armed gangs patrol many streets and even kidnap school children and church pastors in the middle of their church services. Poverty and hunger are on the rise, and the government is accused of enriching itself without providing even the most basic services.

Now the political vacuum left by the murder of Mr Moïse could fuel a cycle of violence, experts warned.

More than two centuries ago, Haitians fought to shake off the yoke of colonial France and put an end to one of the world’s most brutal slave colonies that had brought great fortune to France. What began as a slave revolt at the beginning of the 18th century ultimately led to the breathtaking defeat of Napoleon’s troops in 1803.

But the suffering of the Haitians did not end with the expulsion of the French.

More recently, the country has suffered more than two decades of dictatorship from François Duvalier, known as Papa Doc, and his son Jean-Claude, known as Baby Doc.

In 1990 a poor local priest, Jean-Bertrand Aristide, was elected president. But in less than a year he was ousted in a coup.

The country has not rebuilt since a devastating earthquake 11 years ago, and many say it is doing worse despite billions of dollars in reconstruction aid.

On Wednesday, Mr. Joseph said the president was “cowardly murdered” but the killers “cannot murder his ideas.” He urged the country to “keep calm” and said he would address the nation later that day.

He said the country’s security situation is under the control of the police and army. But international observers warned that the situation could quickly spiral out of control.

Didier Le Bret, a former French ambassador to Haiti, said the situation in Haiti had become so volatile that “many people had an interest in getting rid of Moïse”.

He said he hoped that despite his lack of political legitimacy, Mr. Joseph would be able to rule the country.

Mr Le Bret criticized the international community for ignoring the unstable political situation in Haiti and said it should now help the country “ensure a smooth transition”.

Harold Isaac contributed to the coverage.