Cali - Marxist rebels who seized up to 53 people in a mass kidnapping outside Colombia's second-largest city have freed 15 of their victims, including an American woman, as they fled in the face a huge search-and-rescue operation, authorities said yesterday. The Cuban-inspired National Liberation Army guerrillas took the hostages on Sunday, after erecting makeshift roadblocks along a highway in the Andes mountains near Cali.