Greg Plitt was reportedly filming an advert for a protein shake when he was killed.

Fitness model and actor Greg Plitt, who featured on the cover of numerous magazines, has been killed by a train while filming in Southern California, the US.

Two men were filming Plitt on a railway track north of Burbank station on Saturday afternoon when Plitt, 37, was hit by a southbound Metrolink train.

After interviewing witnesses who saw Plitt standing on the track even as the train’s siren was blaring, investigators ruled out suicide.

It appears he may have believed the train was on a nearby, parallel, track, said Sergeant Scott Meadows of Burbank police.

“It’s like a blind turn,” he said. “When the train came, you might not be able to tell which set the train is on.”

He may have believed the train was on a nearby, parallel, track

It was not immediately clear what the men were filming, but reports have said Plitt was filming an advert for a protein shake when the tragedy happened.

Investigators are trying to determine who directed them to film on the track.

His first name was George, but he was known publicly by his middle name, Greg.

The muscular actor and West Point graduate has appeared on more than 200 magazine covers, Bravo’s reality television show Work Out and NBC’s daytime soap opera Days of our Lives, according to a website in Plitt’s name.

Baltimore-born Plitt served in the army for five years after graduating from West Point, the website said.