Two US citizens are among 28 people detained over the assassination of Haiti's president, the chief of national police has said.

Jovenel Moise, 53, was shot dead by suspected mercenaries at his home in Port-au-Prince, the capital of the impoverished Caribbean island, in the early hours of Wednesday.

Officials have said the attack was carried out by "a highly trained and heavily armed group", whose members spoke Spanish or English.

National Police chief Charles Leon paraded 17 of the suspects in front of a journalists at a news conference on Friday alongside passports, assault rifles, machetes, and hammers being used as evidence in the case.

He said that two Haitian-Americans were among those arrested over Mr Moise's murder, including one who used to work as a bodyguard at the Canadian embassy in Port-au-Prince.

Mathias Pierre, Haiti's minister of elections, named the pair as James Solages, 35, and Joseph Vincent, 55. The US State Department said it was aware of reports of the arrests but did not confirm them.

The other 26 detained are from Colombia, Mr Charles said, adding that three other suspects were killed by police and eight are on the run.

"Foreigners came to our country to kill the president," he told reporters.

First Lady Martine Moise was critically injured in the assault at the private residence and was flown to Miami for medical treatment.

US State Department spokesman Ned Price told reporters that the US embassy in Haiti was restricting movements of direct-hire US citizens at the site and their family members until further notice.

Two of the six suspects were arrested after a crowd found them hiding in bushes in Port-au-Prince.

Witnesses said locals grabbed the pair by their shirts and trousers, pushing them and sometimes slapping them. The two were later arrested when police arrived and were placed in the back of a truck.

Haiti's Prime Minister Claude Joseph has appealed to citizens to hand over suspects to officers and not to attack them.

Earlier on Thursday, hundreds of residents gathered outside a police station in the capital where some of those thought to be involved were being held.

People in the crowd shouted "burn them" and set fire to several abandoned cars riddled with bullet holes they believed belonged to the suspects.

At a news conference, Mr Charles asked people to stay calm, go home and let police do their work as he warned that authorities needed evidence they were destroying, including the burned cars.

Prime Minister Claude Joseph has assumed leadership of the country with the backing of police and the military.

On Thursday, he asked people to reopen businesses and go back to work as he ordered the reopening of the international airport, a day after declaring a two-week state of siege.

Wednesday's atrocity was condemned by Haiti's main opposition parties and the international community, including US President Joe Biden and UK Prime Minister Boris Johnson.

In February, Sky News chief correspondent Stuart Ramsay reported from Haiti about the violence and unrest gripping the nation.

The impoverished Caribbean country had grown increasingly unstable and disgruntled under Mr Moise's rule, bringing an eruption of protests, kidnappings, and organised crime.

In recent months, opposition leaders demanded he step down, arguing that his term legally ended in February.

But Mr Moise and his supporters maintained that his term began when he took office in early 2017 since an interim government ran the country for a year after his election victory in 2016.

Mr Moise had been ruling by decree for more than a year after the country failed to hold elections, which led to parliament being dissolved in January 2020.

Haiti was scheduled to hold general elections later this year.