Authorities believe 62-year-old William Spengler, who served 17 years in prison for the 1980 hammer slaying of his grandmother, set fire to a car and house to lure firefighters to his house. The fire destroyed four homes and damaged four others.
Two firefighters were declared dead at the scene, and two others remain hospitalized in stable condition Tuesday. An off-duty police officer was also injured. Spengler was found dead from a self-inflicted gunshot wound to the head.
Police believe the remains are those of Spengler's 67-year-old sister, Cheryl, who lived with Spengler. A medical examiner will need to determine the identity.
Police also said Tuesday that a rambling two-to three-page typewritten note from Spengler had been left behind. The note described how he wanted to burn down the neighborhood and "do what I like doing best, killing people."
Spengler's note didn't give a motive for the shootings, Police Chief Gerald Pickering said. He would not reveal the note's full content or say where it was found.
Weapons have also been recovered, including a military-style .223-caliber semiautomatic Bushmaster rifle with flash suppression, the same make and caliber weapon used in the elementary school massacre in Newtown, Conn., Pickering said. Police believe the firefighters were hit with shots from the rifle, given the distance, but the investigation was incomplete.
The Associated Press contributed to this report.