William Spengler, the killer of two New York State firefighters, apparently left a chilling note before opening fire on first responders earlier this week.
An ex-con with the same military-style rifle used in the Connecticut school shooting, Spengler typed a note pledging to burn down his neighborhood.
He said he was going to "do what I like doing best, killing people," police said as another body, believed to be the gunman’s missing sister, was found.
Spengler, 62, served 17 years in prison for manslaughter in the 1980 hammer slaying of his grandmother. He set his house afire before dawn Monday.
At that point, he took a revolver, a shotgun and a semiautomatic rifle to a sniper position outside, Webster, N.Y., Police Chief Gerald Pickering said.
He shot dead two firefighters responding to the fire.
The death toll rose to three as police revealed that a body believed to be his 67-year-old sister, Cheryl Spengler, was found in his fire-ravaged home.
Authorities say he sprayed bullets at the first responders, killing two firefighters and injuring two others who remained hospitalized Tuesday.
Those two victims are awake, alert and expected to survive. He then killed himself as seven houses burned on a sliver of land along Lake Ontario.
Police recovered a military-style .223-caliber semiautomatic Bushmaster rifle with flash suppression, the same make and caliber weapon used in Newtown, Conn.
The chief said it was believed the firefighters were hit with shots from the rifle given the distance but the investigation was incomplete and ongoing.
"He was equipped to go to war, kill innocent people," the chief said.
The 2-3 page typewritten rambling note left by Spengler did not reveal what set off the killer or provide a motive for the shootings, Pickering said.
He called the attack a "clear ambush on first responders."
He read only one chilling line: "I still have to get ready to see how much of the neighborhood I can burn down, and do what I like doing best, killing people."