Ebola virus
© CDCElectron micrograph of Ebola virus
Two Peace Corps volunteers were moved into isolation Wednesday and under observation after being exposed to a person who later died of the deadly Ebola virus, a Peace Corps spokeswoman said.

"Two Peace Corps volunteers have had contact with an individual who later died of the Ebola virus," the spokeswoman said. "These volunteers are not symptomatic and are currently isolated and under observation."

The spokeswoman said the volunteers will return to the United States after they are cleared to travel.

Earlier Wednesday the U.S. Peace Corps said it was pulling 340 volunteers from Liberia, Sierra Leone and Guinea because of the spreading Ebola virus that has killed 672 people in the three countries since February.

"The Peace Corps today announced that it is temporarily removing its volunteers from Liberia, Sierra Leone and Guinea due to the increasing spread of the Ebola virus," the group said in a statement.

The Peace Corps currently has 102 volunteers in Guinea, 108 in Liberia and 130 in Sierra Leone working in the areas of education, health and agriculture.

The State Department has confirmed that one U.S. citizen died from Ebola in Nigeria after being infected in Liberia. Two other American aid workers infected with Ebola - Dr. Kent Brantly and missionary Nancy Writebol - are in serious condition, but have shown slight improvement.

They were part of a team in Liberia from North Carolina-based Christian relief groups Samaritan's Purse and SIM.