Firefighters from Bocas del Toro responded to the incident Saturday night.
The injured were people passing by the incident who tried to help those inside the truck.
The injured have been taken to the David Hospital in Chiriquí where they are being treated for burns.
The names of those injured are: Amílcar Espinoza, 53, the director of the prison in Changuinola, Dr. Larkin Zapata, Diogenes Bellido, 38, a nursing technician, and José Díaz, 53. The names of those killed in the accident have not been released.