(CNN) -- Gunmen launched grenades and used machetes against Muslims being evacuated in a truck convoy in Central African Republic, killing at least three children and 19 adults, a humanitarian group said Saturday. At least 23 more people, including children, were injured in Friday's attack and were being treated in a hospital in Bouar, in the northwestern part of the country, said Michael McCusker with Save the Children in Bangui, the nation's capital. The African country has been wracked with such serious religious and ethnic violence, including between Muslims and Christians, that the United Nations has said it fears a genocide could be brewing, and aid groups warn of a humanitarian crisis."It is a sign of the still fraught and highly dangerous situation," aid leader saysAttackers strike a convoy carrying Muslims, Save the Children group saysThe African country is wracked by violence between Christians and MuslimsAt least 23 more people are injured and being treated at a hospital the group supports
The Bouar hospital treats both Christians and _, the group said.