The US-based Christian Aid Ministries, which claimed it had direct knowledge of the incident, said that the kidnapping occurred when the missionaries were on their way home from building an orphanage.
“This is a special prayer alert," the one-minute message said. “Pray that the gang members would come to repentance.”
A US government spokesperson told the Associated Press that officials were aware of the reports but declined to provide further comment.
“The welfare and safety of US citizens abroad is one of the highest priorities of the Department of State,” they said.
A statement from the Ohio-based ministry says: “The group of 16 US citizens and one Canadian citizen includes five men, seven women, and five children.
“Join us in praying for those who are being held hostage, the kidnappers, and the families, friends, and churches of those affected,” the statement continues. “Pray for those who are seeking God’s direction and making decisions regarding this matter.”
The missionaries were traveling by vehicle to Titanyen, north of the capital Port-au-Prince, after visiting an orphanage in the Croix des Bouquets area. They were abducted along the route on Saturday.
The Washington Post reports that one of the abducted Americans posted a call for help in a WhatsApp group as the kidnapping was occurring.
“Please pray for us!! We are being held hostage, they kidnapped our driver. Pray pray pray. We don’t know where they are taking us,” the message read.
Gang-related kidnappings are a growing problem in Haiti, with authorities saying that groups have demanded ransoms ranging from a couple of hundred dollars to more than $1m to free captives.
Some reports indicate this latest kidnapping is the work of the 400 Mawozo gang, known to operate in the same area.
The gang was blamed for kidnapping five priests and two nuns earlier this year in Haiti. Police in Haiti have also blamed 400 Mawozo for the latest kidnapping.
“This is the type of kidnapping that 400 Mawozo do; we call it a collective kidnapping where they kidnap an entire bus or car,” Gedeon Jean, who runs the Center for Analysis and Research in Human Rights in Port-au-Prince, which monitors kidnapping in the country, told The Miami Herald.
Mr Jean said the gang is responsible for about 80 per cent of the kidnappings taking place in Haiti.
At least 328 kidnapping victims were reported to Haiti's National Police in the first eight months of 2021, compared with a total of 234 for all of 2020, according to a report issued last month by the UN Integrated Office in Haiti known as BINUH.
“Political turmoil, the surge in gang violence, deteriorating socioeconomic conditions – including food insecurity and malnutrition – all contribute to the worsening of the humanitarian situation,” BINUH said in its report.
“An overstretched and under-resourced police force alone cannot address the security ills of Haiti.”
Gangs have been accused of capturing schoolchildren, doctors, and police officers, and as in the case of the missionaries, have taken busloads of passengers in recent months.
Some incidents, such as when five priests and two nuns were kidnapped in April, have prompted protests over the lack of security in the country, which has long suffered from poverty.
The latest reported kidnapping came just days after high-level US officials visited Haiti and promised more resources for the country’s National Police, including another $15m (£11m) to help reduce gang violence.
The security situation in recent months has displaced thousands of Haitians who now live in increasingly unhygienic temporary shelters, prompting the UN Security Council to unanimously agree on Friday to extend its political mission in the country.
Additional reporting by AP