March 3 (UPI) -- Doctors Without Borders pulled out of a Nigerian town after a nearby attack by Boko Haram militants killed at least three U.N. aid workers the day before.
Medical activities in Rann were suspended and 22 Nigerian and international staff evacuated, a Doctors Without Borders said in a release.
Three U.N. aid workers, four soldiers and four mobile police were among the dead in the attack on a military base in Borno, a state in northeastern Nigeria. Another U.N. aid worker is missing.
Doctors Without Borders treated nine wounded patients, according to a release. It's still unclear exactly how many people were killed and injured.
"We are deeply shocked by the loss of three humanitarian colleagues in Rann," said Doctors Without Borders International President Dr. Joanne Liu in the release. "These tragic deaths reflect the ruthless violence which the people trapped in Borno face daily."
Prior to Thursday's attack, the roughly 40,000 people living in Rann were relying almost entirely on Doctors Without Borders' services to access health care, the group said.
"Leaving our patients, which include 60 children currently enrolled in our nutrition program, without medical assistance, is an extremely painful decision," said Kerri Ann Kelly, Doctors Without Borders emergency coordinator in Nigeria. "We will continue to evaluate how the situation evolves and we will return as soon as the conditions allow."