An American nurse and her daughter have been abducted in Haiti, in the latest kidnapping episode to draw international notice, as a resurgence of violence grips the capital, Port-au-Prince.

In a brief statement on Saturday, El Roi Haiti, a faith-focused humanitarian organization, identified the woman as Alix Dorsainvil, the group’s community nurse and the wife of the group’s director. She and her child were taken from El Roi’s campus near the capital on Thursday, according to the statement.

No further details have been made public.

“We are aware of reports of the kidnapping of two U.S. citizens in Haiti,” a U.S. State Department official told The Times by email, adding that U.S. officials were working with their Haitian counterparts and declining to comment further on the matter.

Kidnappings in recent years had become a part of daily life in Port-au-Prince, where gangs have taken over many parts of the city. But, recently, the capital experienced a sharp decline in abductions, according to a report in early July from CARDH, a Haitian human rights group.

The reason: Violence was being met with violence. In a vigilante campaign known as “bwa kale,” civilians took up arms to reclaim some areas of the capital from gangs that have inflicted terror on them for nearly two years.

With the government overpowered and unable to protect its citizens, the movement began to round up and kill presumed gang members in gruesome executions — sometimes chopping off their limbs, other times dousing them with gasoline and burning them alive.

As vigilantism rose, gang violence appeared to subside.

“Fear has changed sides,” the CARDH report said.

But since the document came out, terror seems to have changed sides once more. In recent weeks, local groups have documented a spike in kidnappings and killings of civilians. Between May and mid-July, at least 40 people were abducted and 75 murdered. The case of Ms. Dorsainvil and her child, among others, might signal the end of Haiti’s brief period of respite.

Tensions soared last week when dozens of Haitians sought refuge in front of the U.S. embassy in Port-au-Prince, attempting to flee the violence caused by the Kraze Baryè gang, a group that has been responsible for several high-profile kidnappings since June, including that of a famous radio host and her husband, the former head of Haiti’s electoral council.

Soon after, agents of the national police used tear gas to disperse the group of residents.

“The authorities are abandoning the population,” said Pierre Espérance, executive director of the National Human Rights Defense Network, which last week called Vitel’Homme Innocent, the leader of Kraze Baryè, “the protégé” of high-ranking officers at the Haitian police, including its acting director general. “The gangs are protected by the state authorities and many members of the police force.”

On July 20, CARDH predicted a rise in violence if better security measures were not adopted. The group cited, among other reasons, the weakening of the “bwa kale” movement and the gangs’ need to make up income lost after the earlier drop in kidnappings. (According to rights groups, relatives of victims are often asked to pay up to $1 million in ransom.)

On Thursday, the State Department ordered nonemergency embassy personnel and their families to evacuate; it also advised all U.S. citizens in Haiti to leave “as soon as possible.”

Another kidnapping case drew worldwide attention in 2021, when 17 missionaries, mostly Americans, and their family members were abducted as they were leaving an orphanage in Port-au-Prince. Five hostages were released soon after; the rest managed to escape months later.

“The gangs do whatever they want, whenever they want,” Mr. Espérance said. “No one is safe, whether foreigner or Haitian.”

Harold Isaac in Port-au-Prince contributed reporting.