LINDEN, N.J. — Authorities are investigating what led to an off-duty police officer to be struck and killed by a New Jersey Transit train.

A vigil is planned Tuesday night for 45-year-old Linden Police Officer Daniel Kuczynski in the city’s Dobson Park. He was hit by a New York-bound NJ Transit train carrying about 800 passengers just west of the Linden station on Monday morning.

The 20-year veteran of the department had served as director of the city’s Police Athletic League for the past nine years.

Police Chief Jonathan Parham calls it a “painful loss.”