Police arrested a man who allegedly stabbed his grandfather to death inside his Long Island home.

John Pilgrim was inside his home on Hounslow Road in Shirley Monday evening, when his grandson stabbed him in an attack just before 8 p.m., according to Suffolk County police.

The 80-year-old Pilgrim was pronounced dead at the scene. His grandson, 34-year-old Christopher Clarke, ran from the home immediately after the alleged killing. Police said that after an investigation, Clarke was found at the Long Island Rail Road station in the town about two hours later.

He was arrested and charged with second-degree murder, and was scheduled to be arraigned later Tuesday. Attorney information for the Brooklyn resident was not immediately made available.