Long says one relief group started a measles vaccination campaign at the camps, on Wednesday, after violence delayed the group's initial attempt.
"Doctors Without Borders tried to start that vaccinating children at that camp last week but stopped the program because of violence, at the time," Long said. "Their spokesman said there were stray bullets flying through that clinic and several children were killed in the camp, at that time."
Ted Chaiban, emergency programs director for the United Nations Children's Fund, says the unrest is having an especially hard impact on children.
"Children have seen unspeakable violence in the CAR. There are a million people displaced in the Central African Republic, 500,000 of them children," he said.
UNICEF and its partners say they have verified the killings of at least 16 children in Bangui, since early December, including two who were beheaded.
"We've seen torture; we've seen attacks against children," Chaiban said. "They are recruited, we estimate between 3,500 and 6,000 children who are with different armed forces, but also they are exposed to disease, they are out of school, and it's really a very difficult place to be a child right now."
Chaiban says the U.N. agency needs about $64 million to provide humanitarian assistance in CAR this year, but so far, has received only one-third of those funds.