NBC4 Helicopter Crash: NTSB Says Video From Cockpit Will Be Key to Investigation

The Los Angeles news helicopter that crashed while covering a deadly bus accident is under investigation by the National Transportation Safety Board ... and one member of the agency shared what may be a key piece of evidence -- though the investigation is still in its early stages.

NTSB Investigator-in-Charge Fabian Salazar addressed the media ... noting the NTSB is in the early stages of its investigation. At this time, NTSB and the Federal Aviation Administration are gathering factual information on the crash.

Salazar said the preliminary report on the crash will take at least 30 days to come out. The final report with the probable cause could take up to 18 months.

Video from the incident could make a huge difference, Salazar notes ... especially once video from inside the helicopter is analyzed -- because he says the NTSB's lab may be able to identify issues with the craft based on the noises of the engine and warning sounds from the tech in the helicopter.

As we've reported ... the crash went down Tuesday evening during news coverage. Shortly after the incident, anchor Colleen Williams told viewers the station had "lost contact with our people."

Three people died in the fiery Chatsworth crash ... reporter Eliana Moreno, pilot George Marciniw, and Edy Gutierrez Mejia. Marciniw had more than 3 decades of flight experience.

NBC Los Angeles and Telemundo 52 wrote in a joint statement ... "We are deeply saddened to share that a helicopter providing aerial news coverage for NBC4 and Telemundo 52 was involved in a fatal accident in Los Angeles on Tuesday evening. We extend our heartfelt condolences to the families, friends and colleagues of those who lost their lives."