CCSD deputies and fire personnel discovered all victims deceased on the scene, although their cause of death is not yet known and their identities have not been released.
An NTSB investigator is expected to arrive at the crash scene on Monday, according to a statement from Jennifer Gabris, an NTSB spokesperson.
“Once on scene investigators will begin the process of documenting the scene and examining the aircraft,” Gabris told CNN in an email. “Part of the investigation will be to request radar data, weather information, air traffic control communication, airplane maintenance records and the pilot’s medical records.”
“NTSB investigators will look at the human, machine and environment as the outline of the investigation,” she added.
A preliminary report will be available from the agency after 15 days and the full investigation will take between 12 to 24 months to complete, according to Gabris.
The Colusa County Sheriffs Office is interviewing people who may have seen the helicopter crash and are asking anyone who has information about the incident to contact them.