Haitian President Jovenel Moise has been assassinated at his home, interim Prime Minister Claude Joseph said.
A group of unidentified individuals attacked the private resident of Moise overnight on Wednesday and shot him dead, Joseph said.
The first lady was hospitalised in the attack.
Moise had been ruling Haiti, the poorest country in the Americas, by decree after legislative elections due in 2018 were delayed and following disputes on when his own term ended.
Joseph said he was now in charge of the country.
“All measures are being taken to guarantee the continuity of the state and to protect the nation,” Joseph said. Gunshots could be heard throughout the capital.
The attack occurred amid a rising wave of politically linked violence in the impoverished Caribbean nation. With Haiti politically divided, and facing a growing humanitarian crisis and shortages of food, there are fears of widespread disorder.
Port-au-Prince had been suffering an increase in violence as gangs battle one another and police for control of the streets.
That violence was fuelled by an increase in poverty and political instability.
Moise has faced fierce protests since he took office as president in 2017, with the opposition accusing him this year of seeking to install a dictatorship by overstaying his mandate and becoming more authoritarian – charges he denied.