The air ambulance flight departed San Juan (SJU), Puerto Rico about 23:15. The pilot stated that while en route they received a Left GEN OFF annunciator light. The Quick Reference Handbook (QRH) was completed and the flight continued with the right generator functioning normally. The decision was made to divert to Punta Gorda-Charlotte County Airport, FL (PGD). The flight continued and approximately 1 hour 40 minutes into the flight the captain noticed several annunciations, and messages that both GPS receivers were not receiving input from the #2 electrical bus. The right generator was checked and it appeared to be functioning normally, but when the captain later checked the battery gauge it was reading 11-14 volts. He declared an emergency with ATC and advised the controller of their situation, and requested a vector to the nearest airport. The flight was vectored to the Exuma International Airport (GGT), Bahamas and while fully configured for landing while flying at 1,500 feet, the airplane, “…became dark.” No lights were on at the airport and the captain spotted what he thought was the runway. After touchdown, he applied full brakes and the thrust reversers but they did not deploy. At some point during the landing roll the right main landing gear tire blew and the airplane departed the right side of the runway. After coming to rest the captain attempted to secure both engines but the left engine continued to operate. Findings and Probable Cause could not be determined as the aircraft was stripped of its components, instrumentations, manuals and CVR by the owners of the aircraft, without permission or authorization from the Accident Investigation Personnel