Washington DC - A US couple was among three missionaries shot and killed by a gang outside a church in the Haitian capital, which has endured months of extreme violence with deadly assaults on hospitals, prisons, and government buildings.

Missions in Haiti, an Oklahoma-based nonprofit founded in 2000, said Davy and Natalie Lloyd and a third person were killed in Port-au-Prince by armed men on Thursday evening.

The third victim was identified by US media outlets as Jude Montis, the Haitian director of Missions in Haiti.

"Davy and Natalie and Jude were shot and killed by the gang about 9 o'clock this evening," Missions in Haiti said on its Facebook page on Friday. "We all are devastated."

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It said that the missionaries were ambushed by a gang traveling in three vehicles.

"Davy was taken to the house tied up and beat," it said. "The gang then took our trucks and loaded everything up they wanted and left."

Members of another gang then arrived and "went into full attack mode," the group added.

Responding to the deaths, the White House called for the swift deployment of a Kenyan-led multinational force in Haiti to tackle rampant gang violence.

"The security situation in Haiti cannot wait," said a National Security Council spokesperson, stressing that President Joe Biden had pledged to support the "expedited deployment" of the force in talks with Kenya's president on Thursday.

"Our hearts go out to the families of those killed as they experience unimaginable grief," the spokesperson added.

A spokesman for UN Secretary-General Antonio Guterres also expressed condolences, calling it "just another example of the violence that spares no one in Haiti."

The main airport partly reopened this week after being closed since early March, after the powerful and well-armed gangs that control much of the country went on a coordinated rampage they said was aimed at toppling then-prime minister Ariel Henry.

Henry, who has since resigned, had himself been unable to return home while abroad at the time of the attacks due to the gangs' activity.

Haiti has been wracked for decades by poverty, natural disasters, political instability, and violence. It has had no president since the assassination of Jovenel Moise in 2021, and it has no sitting parliament.

The last election was in 2016, and a new transitional government council is struggling to assert its authority, with food running short, tens of thousands fleeing their homes, and the healthcare system on the brink of collapse.

Kenyan President William Ruto vowed during his visit to Washington that his country's security deployment to Haiti would seek to crush the gangs.

The Biden administration had searched extensively for a country to take the lead on the mission to Haiti after having ruled out sending in US forces, who have a long history of intervention in the country.