The plane disappeared from the radar screens late Tuesday, but the debris was not found until Wednesday morning because the crash site is in a densely forested region. There were no survivors, authorities said.
The plane, a single-engine Embraer 821-Caraja, took off from Belem, Para state's capital, and crashed only 20 kilometers away from the city's Monte Dourado airport. The names of the victims were not disclosed.
The plane, which belonged to air charter company Fretax, was transporting nine employees of engineering company Cesbe to the Santo Antonio do Jari hydroelectric power plant, which is being building in neighboring Amapa state.
The cause of the accident remains unknown and will be investigated by aviation authorities.
Both Fretax and Cesbe released statements regretting the incident and saying they are providing assistance to the victims' families.
Fretax said the pilot had been in good health and the plane's inspections were up to date.