Two staff members of the U.S. Embassy in Nigeria were shot and killed along with two police operatives traveling in a convoy, and three others were kidnapped, police in the volatile West Africa nation said Tuesday.

The group was on a humanitarian mission when they were attacked in the Ogbaru Local Government Area of the country's Anambra State, one of the epicenters of separatist violence in the region, said Tochukwu Ikenga, a police spokesman in Anambra.

Ikenga said no U.S. citizen was on the trip.

"We confirm there was an incident May 16 in Anambra state. Mission Nigeria personnel are working with Nigerian security services to investigate," a U.S. State Department spokesperson said. "The security of our personnel is always paramount, and we take extensive precautions when organizing trips to the field. We have no further comment at this time."

Details of the attack were not disclosed. 

A joint team of security forces was deployed to the scene, but arrived only after the assailants escaped with two other police officers and one of the drivers, Ikenga added.

CHILDREN AMONG 15 DEAD IN NORTH NIGERIA BOAT ACCIDENT

"The hoodlums murdered two of the Police Mobile Force operatives and two staff of the Consulate, and set their bodies ablaze and their vehicles," Ikenga said.

It is not immediately clear the nature of the trip embarked upon by the U.S. Embassy staffers in Anambra, nor how many there were in the convoy. 

Ikenga said it was regrettable that "a convoy of such or any related will enter the state without recourse to the police in the area or any security agency."

The attack in Atani Town, located 37 miles from the state capital, further raised concerns about the safety of residents and travelers amid the separatist violence that has become rampant in Nigeria’s southeastern region in recent years.

Nigeria has seen a rash of deadly attacks against remote communities in recent months. 

On Tuesday, gunmen attacked villages in the troubled north-central region, killing 29 people and razing houses, and survivors. 

The gunmen targeted three villages in Plateau state’s Mangu local government area late Monday night, and killed several people either with gunfire or after setting their houses ablaze, one resident said. 

In April, 50 people were killed in two separate attacks authorities believe are linked. 

The Associated Press contributed to this report.