It is understood that around 2.30am a semi-trailer travelling south at El Arish, near Innisfail, collided head on with a mini bus travelling in the opposite direction.
The driver and two passengers of the minibus were declared deceased at the scene.
Two other passengers of the bus were taken to Innisfail Hospital.
The truck driver was not injured.
The Forensic Crash Unit is investigating the cause of the crash.