The cease-fire agreement was signed by representatives of the Muslim-backed Séléka rebel group and anti-Balaka Christian militia in neighboring Republic of the Congo.
Violence broke out in March 2013 when the Séléka group took control of the capital, Bangui, and removed Christian President François Bozizé.
Mohamed Moussa Dhaffane, who led the Séléka delegation at the peace talks, hailed the agreement as a step toward peace. "We have signed this ceasefire today in front of everyone. Our commitment is firm and irreversible."
Anti-Balaka delegation leader Patrick Edouard Ngaissona vowed that those who violated the cease-fire would face arrest.
And yet, hours into the cease-fire, two ex-Séléka soldiers were shot by suspected anti-Balaka fighters in the embattled town of Bambari.
On Thursday, the U.S. Department of State encouraged "all parties to fully implement the terms of the agreement and to move quickly to hold and conclude further talks, to be held in the Central African Republic, on a political way forward."