NJ Transit has confirmed one of two reported instances of a door opening on the wrong side of a train — a case in which a passenger fell out of the train car — during the Monday commute.

A rider on North Jersey Coast Line No. 3515 wrote on Twitter that another passenger fell onto the tracks when the train arrived at Secaucus Junction around 5:40 p.m.

"Thank god he wasn't hurt," @MissDS17 tweeted. The incident was acknowledged by "DK" of NJ Transit's social media team, who said the incident was reported to the "proper department for further investigation."

NJ Transit spokeswoman Lisa Torbic told Townsquare Media that an investigation was immediately started into the incident.

"Preliminary, the cause appears to be human error, but the investigation remains ongoing," Torbic wrote in a message to the station.

Rider @GratefulCommut1 posted a picture of an open door they said was from No. 3721 on the Northeast Corridor at Penn Station New York, from earlier in the commute.

"Thankfully no one was next to it," @GratefulCommut1 tweeted. NJ Transit spokesman Jim Smith on Tuesday said the agency was looking to confirm the incident.

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