A group of American missionaries working in Haiti were kidnapped by a notorious gang amid a sharp rise in abductions and political turmoil in the Caribbean nation, a spokesman for the Haitian Justice Ministry said.

The spokesman didn’t provide more details. But the Ohio-based Christian Aid Ministries said in a statement Sunday that a group that included 16 Americans and one Canadian was kidnapped Saturday morning during a trip to an orphanage. The organization said that five of those who were abducted are children.

“Join...

A group of American missionaries working in Haiti were kidnapped by a notorious gang amid a sharp rise in abductions and political turmoil in the Caribbean nation, a spokesman for the Haitian Justice Ministry said.

The spokesman didn’t provide more details. But the Ohio-based Christian Aid Ministries said in a statement Sunday that a group that included 16 Americans and one Canadian was kidnapped Saturday morning during a trip to an orphanage. The organization said that five of those who were abducted are children.

“Join us in praying for those who are being held hostage, the kidnappers, and the families, friends, and churches of those affected,” Christian Aid Ministries said.

Gédéon Jean of the Center for Analysis and Research in Human Rights, a Port-au-Prince-based organization that tracks kidnappings in Haiti, said the kidnapping was carried out by members of the 400 Mawozo gang.

Mr. Jean said the gang, which controls the Croix-des-Bouquets suburb east of Port-au-Prince, is responsible for about 80% of mass kidnappings in Haiti.

“The gangs are increasingly showing that they are controlling more territory and operating as they like,” said Mr. Jean.

A U.S. Embassy spokesman referred inquiries to the State Department, which said it was aware of reports of the abductions.

“The welfare and safety of U.S. citizens abroad is one of the highest priorities of the Department of State. We are aware of these reports and have nothing additional to offer at this time,” a State Department spokesperson said in a statement on Sunday.

Sen. Rob Portman, an Ohio Republican and a member of the Senate Foreign Relations Committee, expressed concern over the reports. “I have been in touch with the State Dept to encourage them to ensure the safe return of the missionaries,” he said on Twitter on Sunday.

Kidnappings in Haiti have surged this year as the country has been gripped by a deepening political crisis following July’s brazen assassination of president Jovenel Moïse at his home in Port-au-Prince. A range of businessmen, security officials and former Colombian soldiers were arrested, but it remains unclear who was responsible.

A United Nations report presented to the Security Council found that kidnappings rose to 328 in the first eight months of this year compared with 234 during all of 2020 as gangs target everyone from poor street vendors to wealthy businessmen. The U.N. says that gangs control swaths of the country, including about half of the capital, causing fuel shortages and displacing thousands of people while hampering relief efforts during a devastating August earthquake.

The Croix-des-Bouquets suburb east of Port-au-Prince is controlled by the 400 Mawozo gang.

Photo: Dieu Nalio Chery/Associated Press

About 19,000 people have been displaced by gangs since early June, the U.N. says, while charity Doctors Without Borders was forced to close a hospital in August in the capital’s Martissant neighborhood because of violence by gangs, many with ties to powerful politicians.

“The gangs are more arrogant and they control more territory,” said Pierre Esperance, the director of a leading Haitian human rights group. “That is why there are more kidnappings.”

In April, the Vatican said five priests, two nuns and three of their relatives were seized by kidnappers, said to belong to the 400 Mawozo gang, as the clergy went out to the installation of a parish priest. Church institutions suspended their activities for three days, while church bells tolled in protest of the kidnapping. The kidnap victims were eventually released.

The number of kidnappings has picked up in the past two months since Mr. Moïse’s assassination, leading a national union of transportation workers to call for a strike on Monday to protest abductions of its members. In September, 117 people were kidnapped, up from 31 in July, according to the Center for Analysis and Research in Human Rights. Forty-two kidnapping victims so far this year have been foreigners.

“You are so afraid every day. Every time you get home you think, ‘Thank God, I’m here, they didn’t kidnap me,’” said Hans Joseph, a 47-year-old small restaurant owner in Port-au-Prince. “It is getting worse, worse, worse every day.”

The kidnapping on Saturday occurred a day after the U.N.’s Security Council extended for nine months a U.N. mission in Haiti that is working to bring political stability.

It also follows last month’s resignation of the U.S. special envoy to Haiti, Ambassador Daniel Foote, who was appointed after Mr. Moïse’s assassination. Mr. Foote stepped down in protest of the Biden administration’s large-scale deportation of Haitian migrants who had arrived at the U.S. southern border.

—Patrick Saint-Pre, Jim Carlton and Tarini Parti contributed to this article.

Write to José de Córdoba at jose.decordoba@wsj.com and Ryan Dube at ryan.dube@dowjones.com