The ICRC said a 36-year-old volunteer was gunned down in Bangui, the CAR's capital, Sunday. It was the second such death for the agency since last week.
Armed men stormed a Catholic mission in northern CAR housing four members of the ICRC staff. Three members escaped without serious injury in the Saturday attack.
Seleka, a Sunni Muslim rebel coalition, overthrew the government in March 2013. Former President Michel Djotodia, a rebel commander, lost control of the force and the conflict took a turn for the worse when anti-balaka, a Christian militia, took up arms against its Muslim rivals.
The ICRC, Red Crescent Movement, and their international counterparts, called on all parties to the conflict in CAR to respect international laws and spare aid workers from the violence.
"We urgently call on those involved in the fighting to refrain from harming volunteers from the Central African Red Cross Society and other personnel affiliated with the Movement, and to allow them to carry out their life-saving work," they said in a joint statement.