The incident happened around 2:30 p.m. on Commercial St. in Hicksville.
The LIRR says the Ronkonkoma Branch was shut down earlier, but now is experiencing residual delays, about 10 minutes in both directions.
The delays, however, will subside shortly as service through Bethpage has been fully restored.
The investigation remains ongoing.
MORE NEWS: Cardi B, sister, model face lawsuit from Smith Point beachgoers on Long Island
Cardi B, sister, model face lawsuit from LI beachgoers
----------
* More Long Island news
* Send us a news tip
* Download the abc7NY app for breaking news alerts
*Follow us on YouTube