A group of 17 US missionaries - including children - have been kidnapped in Haiti.
They were on their way home from building an orphanage in the capital of Port-au-Prince, Christian Aid Ministries said.
A voice message sent to a number of religious missions said: "This is a special prayer alert. Pray that the gang members would come to repentance."
Haiti has seen a spike in the number of gang-related kidnappings after President Jovenel Moïse was assassinated at his home in July.
A US government spokesperson told the AP news agency: "The welfare and safety of US citizens abroad is one of the highest priorities of the Department of State."
According to The New York Times, they were abducted from a bus that was heading to the airport.
The newspaper said parts of the capital are now so dangerous that many residents have fled - and few pedestrians now venture out during the day.
Haiti is the poorest country in the Americas, and the surge in gang violence has displaced thousands of people.
In August, an earthquake killed more than 2,000 people.