William Spengler, the cold-hearted killer who set his New York home ablaze so he could shoot at volunteer firefighters, left a chilling, rambling note that left no motive behind the bizarre incident.

After setting the fire, Spengler shot at four volunteer firefighters, killing 911 dispatcher Tomasz Kaczowka, 19, and police Lt. Michael Chiapperini, 43. Two other volunteer firefighters were injured and were in the hospital as of Tuesday in stable condition, the Associated Press reported.

Police investigating the murders found the chilling note left by Spengler in the ruins of the Webster, N.Y., home that he shared with his sister, with whom he reportedly often fought.

“I still have to see how much of the neighborhood I can burn down and do what I like doing best: killing people,” the 62-year-old ex-con wrote in the chilling three-page note, the New York Post reported.

The note did not say why Spengler targeted volunteer firefighters who responded to the blaze, but authorities were looking at a connection Spengler’s mother had with the Webster Fire Department. When his mother died, donations were encouraged to be sent to the department in lieu of flowers, the newspaper reported.

“There was no motive in the note. There were some ramblings in there,” Webster Police Chief Gerald Pickering told the newspaper. “It spoke mainly that he intended to burn his neighborhood down and kill as many people as possible.”

Pickering added, “As far as motive, all kinds of speculation, and truthfully, we do not know. They’re trying to draw a nexus between the donations of the mother to the fire department.”

The contents of the chilling note came as investigators identified Spengler’s sister as a possible third victim of his rampage.

The body of Cheryl Spengler, 67, was found in the Webster home, the AP reported.

“We did locate apparent human remains in the ruins of the house at 191 Lake Road,” Pickering told the New York Post. “The assumption is that’s the shooter’s sister.”

The chief said that it’s unclear whether Cheryl Spengler died before or after the fire.

The newspaper said the siblings lived on opposite sides of the house and often fought each other.

William Spengler killed his grandmother in 1980, but pleaded guilty to manslaughter and received a reduced sentenced, the AP reported. Spengler wanted to spare his family a trial, according to the newswire service.

Police said Spengler had enough weapons on him that indicated he intended to inflict more damage before killing himself.

A .223-caliber semiautomatic Bushmaster rifle with flash suppression -- the same weapon used in the Sandy Hook Elementary School shooting in Connecticut by Adam Lanza -- was recovered in the Spengler investigation, Pickering told the AP.

‘‘He was equipped to go to war, kill innocent people,’’ the chief said of Spengler.