The co-pilot of the Germanwings airplane that crashed and killed all 150 people on board intentionally caused the tragedy, French prosecutor Brice Robin said Thursday.
At least three Americans and one Israeli died in the crash in the French Alps on Tuesday.
Robin said that an analysis of the cockpit voice recorder indicated that the German co-pilot, Andreas Lubitz, 28, locked out the captain and remained silent as he brought down the plane to its fiery and deadly destiny.
The only sounds heard from the recorder were screams from passengers after they realized what was happening.
The plane dived 38,000 feet for 10 frightening minutes until it crashed.
Precautionary measures taken after the 9/11 terrorist attacks apparently made it impossible for the captain to re-enter the cockpit after he was locked out.
Cockpit doors were upgraded to prevent terrorists from entering, and entry can be granted only if the pilot agrees. Once the captain had left the cockpit, which is not unusual in a flight, the co-pilot refused him entry as he prepared to commit suicide and murder 150 passengers, the captain and crew.