At about 2222 central time, a Gates Learjet 35A landed gear up at Cancun International Airport. There were no injuries to the two pilots or the three medical personnel on board. The flight, which had originated from the Fort Lauderdale Executive Airport, was cleared for a visual approach to runway 12. The crew said they conducted the landing checklist and noted three green lights in the landing gear position indicator. They were not aware of any problem until feeling the fuselage contact the runway. The airplane slid about 4,000 feet. After the accident, the gear was extended using the emergency extension system.