The abduction occurred about 7 a.m. Thursday in the town of Guachene, near Padilla, when the girl was going to school and was intercepted by the kidnappers in the presence of several of her friends.
In remarks to Blu Radio, Guachene Mayor Francisco Paz accused the FARC guerrilla group of the crime, "by the route (the kidnappers) took" in their flight, although the national ombudsman's office said that groups of drug traffickers are also active in that part of Cauca province.
When news of the kidnapping became known, residents of Guachene came to the area with machetes and sticks but did not find any of those responsible.
Colombia's Defence Minister Juan Carlos Pinzon said on Twitter that an elite police anti-kidnapping unit "is leading the search for little Alejandra in Cauca".
The Revolutionary Armed Forces of Colombia, or FARC, concluded Wednesday at midnight a unilateral nine-day cease-fire it had declared so as not to disrupt the May 25 presidential elections. In 2012 they had supposedly renounced kidnapping for ransom.