Service on the LIRR’s Port Jefferson branch is back on schedule after a vehicle was left on the tracks west of the Syosset station Monday night, authorities said.

At least three trains had been canceled and combined with others after an unauthorized vehicle was found about 5:25 p.m., said spokeswoman Nancy Gamerman of the Metropolitan Transportation Authority.

advertisement | advertise on newsday

Details on whether the driver was found or why the vehicle was there were not immediately available.

Gamerman said trains had been moving around the vehicle on another track. Early on, the incident caused delays of up to an hour.