Symptoms of the illness include headache, diarrhea, vomiting and confusion, according to Fadela Chaib, a spokeswoman for the WHO.
Health officials immediately tested the victims for Ebola, yellow fever and Lassa fever, but they were all ruled out.
According to Tom Skinner, a spokesman for the CDC, "timing of the events, duration between disease onset and death, higher case fatality among children are all suggestive of ingestion or exposure to a contaminant." Still, the CDC remains vigilant for other possible causes.
Some of the victims died in the hospital in Sinoe County, a four-hour drive southeast of the capital city, Monrovia.
Four people have been discharged from the hospital.