The medical charity Medecins Sans Frontieres said on Friday it had suspended its work in the Nigerian town of Rann and evacuated national and international staff after a deadly raid.

Suspected Boko Haram militants killed at least 11 people including three aid workers in an attack on a military barracks in Nigeria’s northeastern Borno state late on Thursday, according to two security reports seen by Reuters.

“Following a violent attack in Rann, Borno state, on Thursday 1 March, Médecins Sans Frontières (MSF) suspended its medical activities in the town and evacuated 22 national and international staff,” MSF said in a statement.

“It is still unclear how many people were killed and injured but before leaving, MSF medical staff treated 9 wounded patients,” it added.