Valmiki Ramayana Aranya Kanda Sarga 33 Shloka 12

एकेन by one alone, रामेण by Rama, क्रूरकर्मणाम् perpetrators of cruel acts, रक्षसाम् demons, चतुर्दश fourteen, सहस्राणि thousand, हतानि are killed, सहदूषणः and Dusana too, खरश्च Khara also.

One Rama alone killed all the fourteen thousand demons including Dusana and Khara, demons capable of fierce exploits.