More than a dozen people who ventured into the Andes Mountains for a purported spiritual retreat have reportedly vanished in circumstances the local mayor is calling “very suspicious.” The group, made up of local families in Venezuela’s Táchira state, followed a woman into the mountains after she told them she’d received a revelation from the Virgin Mary, the BBC reports. A local official was quoted as saying between 16 and 20 people are thought to have embarked on the trip, with a newborn baby and several children among them. Relatives say they’ve not had contact with them since Aug. 22. Local authorities are now using drones and dogs to scour the area around La Grita for any sign of the group. “There are several theories [of what may have happened] but we won’t know what really happened until the investigations have been concluded,” the mayor was quoted saying.