The man, identified by LIRR officials as 51-year-old Ronald Sampson, was taken to Long Island Jewish Hospital, after the incident near 225th Street just before 11 a.m., the FDNY said.
"He was performing track maintenance work with a gang of seven other employees when the incident occurred," LIRR officials said. "Sampson’s fellow employees administered CPR at the scene until the arrival of the emergency medical services that transported him to the hospital."
According to officials, the man was working on the line just east of the Queens Village station, when he came in contact with the third rail.
A second employee, who had tried to help his collegue, was also taken to the hopital as a precaution.
Sampson, of Lake Ronkonkoma, began his career at the LIRR in 2006 as an electric traction helper and was promoted to third railman in 2008, LIRR officials said.
"The entire LIRR is deeply shaken by this tragic loss," LIRR President Helena Williams said in a statement. "Ron was a dedicated employee and family man. It’s a very sad day at the railroad today."
Police and LIRR Safety are investigating the accident.