The medical aid charity Doctors Without Borders (MSF) has suspended its activities in part of the Central African Republic after one of its drivers was killed in an attack on a convoy.
The incident happened on Wednesday in Kouki, some 400km (250 miles) north of the capital Bangui, the group said.
"A well-identified MSF convoy of two vehicles transporting staff and patients was stopped by armed men in Kouki," the group said in a statement.
"The team was forced out of the cars and onto the ground. They were robbed of personal belongings and medication. In the course of the incident, which lasted for more than 40 minutes, one of the drivers was shot and killed."
Michelle Chouinard, the organisation's head of mission in CAR, said the team was subjected to death threats during the attack.
"It is absolutely unacceptable that a team of medical workers and their patients were attacked while returning from providing life-saving medical care," she said.
"It is outrageous that one of our staff members was killed during this act of violence. The MSF team and their patients endured prolonged harassment, including bullets shot close to their heads and repeated verbal threats that they would be killed."
The charity said it was stopping its activities in the area "until it receives adequate guarantees for the safety of its staff and the acceptance of its medical and humanitarian activities".
CAR was plunged into chaos in 2013 when a rebel group, Seleka, toppled president Francois Bozize, triggering a spiral of revenge attacks between the rebels and vigilante groups that left thousands dead and displaced many more. About one in five Central Africans were forced from their homes.
The bloodletting in one of the world's poorest nations was so serious that it triggered a military intervention by former colonial power France and led to the deployment of a UN peacekeeping force.
A peaceful presidential vote held in February was hailed as an important step towards reconciliation.
'We will not be silent'
MSF, which runs 17 projects across CAR, added that it expected "a full inquiry" by police and local authorities into the violence.
Earlier in May, MSF President Joanne Liu called for an end to attacks at the UN Security Council.
"Medicine must not be a deadly occupation," she said. "Medical ethics cannot be buried by war."
She was referring to a recent deadly attack on a hospital in Aleppo, a US attack on an MSF centre in Afghanistan in October 2015,the bombing of an MSF hospital in Yemen, and several strikes on medical facilities elsewhere in Africa.
"We will not leave patients behind. And we will not be silent," Liu said. "Seeking or providing healthcare must not be a death sentence."
Source: Al Jazeera and agencies