Police say a man has been arrested for aggravated unlicensed operation of a vehicle following a fatal crash on the Long Island Expressway in Brentwood.

According to police, Brandon Gillespie was at the wheel of a 2012 Jeep Liberty stopped in the right lane of the eastbound LIE, east of the Sagtikos State Parkway, when the vehicle was rear-ended by a 2016 Ford box truck at approximately 12:45 a.m.

Gillespie, 36, of Smithtown was pronounced dead at the scene by a physician assistant from the Office of the Suffolk County Medical Examiner. The victim's father says he leaves behind a wife and a 1-year-old son.

Bob Gillespie says the family still can't believe what happened to his son.

"I was devastated," Bob Gillespie says. "We haven't stopped crying all day. It was the worst thing that ever happened to us."

The driver of the Ford, Taron Smith, was not injured.

Smith, 31, of Patchogue was arrested and charged with driving without a valid license. Police say Smith had his license suspended for failing to answer a summons.

Smith was also issued multiple summonses for safety violations. He is set to go before a judge at a later date.

Both vehicles were impounded for safety checks.

The eastbound side of the LIE has reopened at Exit 53. It was previously closed for hours due to the incident.

Anyone with information on this crash is asked to call the Third Squad at 631-854-8352.

Brandon Gillespie worked for Optimum, which along with News 12 is owned by Altice USA. He worked in sales at the company's Bethpage headquarters.

Optimum sent out a statement, which says, "We are saddened to learn of the tragic loss of Brandon Gillespie, a valued Optimum team member. His loved ones and colleagues are in our thoughts and prayers during this incredibly difficult time."

"I want him to be remembered as a really wonderful person that worked hard at his jobs," Bob Gillespie says. "He loved his work at Optimum. He liked the people that he worked for and worked with. He was a great father and a great son."