An American woman was kidnapped at gunpoint from Uganda's Queen Elizabeth National Park Tuesday night, Reuters reports. Kimberley Sue Endecott, 35, and her Ugandan driver were on a game drive in the safari park when four gunmen ambushed the vehicle and took them both. An elderly couple at the scene weren't abducted and reported the incident to police. The suspects quickly used one of the victims' phones to call authorities and demand a ransom of $500,000, NBC News reports. A search has been launched, and police have blocked the nearby border with Congo in an attempt to trap the group. (More Uganda stories.)