DAKAR, Senegal (AP) — Aid group Doctors Without Borders said Friday it’s suspending non-emergency services in Burkina Faso after gunmen killed two of its staff there.

“This measure, necessary for the time of mourning, is essential to analyze the risks to which our teams are currently exposed,” the group said on Twitter, adding that it will only respond to life-saving emergencies in Burkina Faso for an indefinite period.

Earlier this month gunmen fired on a vehicle carrying a medical team in the western region of Boucle du Mouhoun, killing two of the group’s employees while two others escaped.

The west African nation has been wracked by violence linked to al-Qaida and the Islamic State group for seven years, which has killed thousands and displaced nearly 2 million people, creating a humanitarian crisis.

The fighting has brought tens of thousands to the brink of starvation as jihadis besiege towns. Nearly 600,000 people live under blockade, which has reduced aid access by 60%, according to an unpublished report for aid workers seen by the Associated Press.

Doctors Without Borders, also known by its French acronym MSF, was operating in some of the most volatile areas in the country, reaching more than one million people with some 1,000 staff.

No one has claimed responsibility for the MSF staff killings. A conflict analyst said the incident indicates the challenges for aid workers operating among a host of armed groups, including the government army and volunteers fighting on its side.

“With multiple armed actors the risks are high, and we can’t say for sure jihadists are the ones responsible,” said Rida Lyammouri, senior fellow at the Policy Center for the New South, a Moroccan-based think tank.

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