By Elisabeth Smith

(CBS13) — A trial is now underway for the man accused of a Paris train attack that was stopped by three Sacramento friends. 

A 31-year-old Islamic State operative is facing terrorism charges for the 2015 attack. Prosecutors say he intended to “kill all of the passengers.”

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US Army Specialist Alek Skarlatos (L), US Air Force Staff Sergent Spencer Stone (C), Anthony Sadler (R), the three Americans who helped stop a terrorist attack in August 2015 on a train in France. (LIONEL BONAVENTURE/AFP via Getty Images)

Alek Skarlatos, Anthony Sadler and Spencer Stone were traveling through Europe back in Aug. 2015. The three childhood friends were thrust into the international spotlight when they jumped into action and stopped a gunman on the train, saving more than 500 lives.

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They re-enacted the encounter in the movie “The 15:17 to Paris,” which was directed by Clint Eastwood and released earlier in 2018.

Photos: Sacramento Hometown Heroes Parade

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All three are expected to testify. The trial could last a month.