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A passenger traveling along the same route the night that Amtrak Train 188 derailed in Philadelphia told NBC News that an object hit his train, shattering the window.

The account from Johns Hopkins student Justin Landis makes him the third person to report a projectile hitting a train Tuesday night in that area, and comes a day after the National Transportation Safety Board said investigators were working to determine whether something struck the doomed Amtrak train before it derailed. Eight people were killed and about 200 others were injured in the accident.

Landis was traveling on southbound Amtrak Acela 2173 and nearing the Philadelphia 30th Street Station around 9:20 p.m. when he was jolted by the sound of an object hitting and shattering the window of his train car. The passenger sitting next to Landis told him he had seen a rock.

"After I heard about the derailment, I was pretty concerned about what happened," Landis told NBC News. Hoping to find out if the events were connected, he tweeted photos of the damage he saw on board Acela 2173.

Another passenger, Madison Calvert, was sitting by the window that shattered and told NBC News the noise of the object hitting the train was startling.

"I thought it was a rock or a battery," he said. "It sounded like a rock hitting a windshield."

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Calvert, a vice president of sales for a software company, said he has ridden Amtrak for the past 10 years at least twice a month.

"I've never had a window broken," he said.

An assistant conductor on Amtrak 188 told investigators that she thought she heard the engineer say an object had hit the locomotive before it crashed shortly before 9:30 p.m. Meanwhile, a local Southeastern Pennsylvania Transportation Authority (SEPTA) engineer also said his train was hit — either by a rock, or shot at, according to NTSB official Robert Sumwalt.

Landis, who was traveling from New York to Baltimore, said that when his train was about 20 minutes away from the Philadelphia station, passengers heard a "loud noise."

"At the time, I was in shock," he said. "I had no idea what had happened."

As the train pulled into the station in Philadelphia, the passenger next to Landis went to get the conductor.

"The conductor got two or three Amtrak police cops who came on board, checked out the shattered glass, and then got off," he said. "They kind of shrugged it off, like it was no big deal."

The glass had an approximately 6-inch-long crack in it, Landis said.

"If it was just some kid with his friends throwing rocks at the train, it's tragic. It's really, really tragic," he said.

Brandon Bostian, the engineer of Amtrak 188, was interviewed by federal investigators, who say the train was hurtling at 106 mph as it traveled on a sharp curve — more than twice the speed limit for that section of track. Bostian has said he doesn't remember what happened.

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— Katie Wall, Emmanuelle Saliba and Elizabeth Chuck