A man was struck and killed Thursday by an LIRR train in Sayville in what was also investigated as part of an attempted bank robbery case, authorities said.

The crew of the Babylon-to-Patchogue train made the report about a person possibly struck at 4:55 p.m. near the Cherry Avenue crossing, just west of the Sayville train station, Long Island Rail Road spokesman Salvatore Arena said.

A body was found in the area, and Suffolk detectives were at the scene to determine if the man also was the suspect in the attempted robbery of a Citibank branch office in Melville about 11:25 a.m. Thursday, according to a MTA police source.

Investigators determined it was not the same man, the source said.

A Suffolk police spokeswoman said she could not confirm that detectives were involved.

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The train’s engineer saw the man jump from behind bushes into the path of the train, the MTA police source said.

Service on the Montauk line, which had been suspended in both directions east of Babylon, resumed just after 6:15 p.m., Arena said. The LIRR warned of lingering delays of up to 90 minutes.

The disruption came as Long Islanders were trying to get to New Year’s Eve parties and the lowering of the crystal ball in Manhattan.

The LIRR had scheduled extra trains in both directions to accommodate party goers.