(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.
The convoy was carrying mostly Muslim families from the village of Vakap when a grenade was launched into the trucks, said officials with Save the Children, a U.K.-based aid group.
Attackers hacked many victims with machetes, the group said.
The mostly Muslim families in the convoy were being evacuated from violence and were ultimately destined for refuge in neighboring Cameroon.
"It is a sign of the still fraught and highly dangerous situation in the Central African Republic that children and their families have been attacked and killed while trying to evacuate to safety," said Robert Lankenau, the group's director in the country.
The Bouar hospital treats both Christians and Muslims, the group said.
Security has deteriorated since the country's interim leaders, President Michel Djotodia and Prime Minister Nicolas Tiangaye, announced their resignation at a regional summit in Chad this month.
Chaos struck the Central African Republic last year after a coalition of rebels dubbed Seleka ousted President Francois Bozize, the latest in a series of coups since its independence.
Rebels infiltrated the capital in March, sending Bozize fleeing to Cameroon.
Djotodia, one of the Seleka leaders, then became interim president in a coup.
Since then, political turmoil and violence has spread. Seleka is a predominantly Muslim coalition. To counter the attacks on their communities, Christians assembled vigilante groups and fought back.
The violence prompted U.N. fears about a genocide brewing.
At least 1,000 people have died in the violence, and some 958,000 more people, many of them children, have been forced from their homes within the Central African Republic, according to the United Nations' refugee agency, UNHCR.
There are also more than 86,000 refugees in Cameroon, Chad, the Democratic Republic of the Congo and the Republic of the Congo who fled the Central African Republic in 2013, the UNHCR said Friday.
Some 100,000 people have gathered at a makeshift camp by the international airport in Bangui, seeking refuge from the violence.
French troops have deployed under a U.N. mandate to assist African peacekeepers.