The government of Haiti declared a 72-hour state of emergency on Sunday after armed gangs stormed a major Port-au-Prince prison. At least 12 people were killed and about 3,700 inmates escaped in the jailbreak.
Gang leaders say they want to force the resignation of Prime Minister Ariel Henry, who had travelled abroad.
The groups aiming to oust him control around 80% of Port-au-Prince.
Violent gang wars have killed thousands in the country since 2020.
A government statement said two prisons – one in the capital and the other in nearby Croix des Bouquets – were stormed over the weekend.
It said the acts of “disobedience” were a threat to national security and said it was instituting an immediate night-time curfew in response, which started at 20:00 local time (01:00 GMT on Monday).
Haitian media reported that other police stations were attacked, distracting authorities before the coordinated assault on the jails.
Among those detained in Port-au-Prince were gang members charged in connection with the 2021 killing of President Jovenel Moïse.
The latest upsurge in violence began on Thursday, when the prime minister travelled to Nairobi to discuss sending a Kenya-led multinational security force to Haiti.
Gang leader Jimmy Chérizier (nicknamed “Barbecue”) declared a co-ordinated attack to remove him.
“All of us, the armed groups in the provincial towns and the armed groups in the capital, are united,” said the former police officer, who is thought to be behind several massacres in Port-au-Prince.
Haiti’s police union had asked the military to help reinforce the capital’s main prison, but the compound was stormed late on Saturday.
On Sunday the doors of the prison were still open and there were no signs of officers, Reuters news agency reported. Three inmates who tried to flee lay dead in the courtyard, the report said.
A journalist for the AFP news agency who visited the prison saw around 10 bodies, some with signs of injuries caused by bullets.
One volunteer prison worker told the Reuters news agency that 99 prisoners – including former Colombian soldiers jailed over President Moïse’s murder – had chosen to remain in their cells for fear of being killed in crossfire.
The US embassy in Port-au-Prince on Sunday urged its citizens to leave Haiti “as soon as possible”. The French embassy said it was closing visa services as a “precaution”.
Violence has been rife since President Moïse’s assassination at his home in 2021. He has not been replaced and elections have not been held since 2016.
Under a political deal, Mr Henry was due to stand down by 7 February. But planned elections were not held and he remains in post.
On Monday, Kenyan authorities said the prime minister had returned to Haiti.
Speaking to the BBC’s Newsday, Claude Joseph – who was serving as acting prime minister when President Moïse was assassinated and who is now head of the opposition party called Those Committed to Development – said Haiti was living through a “nightmare”.
Mr Joseph said Prime Minister Henry wanted “to stay as long as possible in charge”.
“He agreed to step down on 7 February. Now he decides to stay, despite the fact that there are huge protests throughout the country asking him to step down – but it’s unfortunate that now those criminals are using violent means to force him to step down.”
In January, the UN said more than 8,400 people were victims of Haiti’s gang violence last year, including killings, injuries and kidnappings – more than double the numbers seen in 2022.
Many health facilities have stopped operating because of the bloodshed.
Anger at the shocking levels of violence, on top of the political vacuum, have led to several demonstrations against the government, with protesters demanding the resignation of the prime minister.