Threatening note: Gunman penned details of deadly plans before setting fire WEBSTER, N.Y. - The gunman who killed two firefighters during a pre-dawn ambush on emergency responders in suburban Rochester, N.Y., apparently mapped out a plan and left behind a note outlining his "clear intent" to burn his neighborhood to the ground and "do what I like doing best, killing people," authorities said. A lone gunman, identified as William Spengler, set his home and a car on fire on Monday in what police called "a clear ambush on first responders." Spengler was found dead at the scene. Two firefighters were killed; two others were seriously wounded. The two to three page note contained the shooter's "clear intent" to ambush first responders but did not reveal the shooter's motive. The police chief said that the shooter's motive may have taken root more than 30 years ago when the police department arrested Spengler for murdering his grandmother. There was no motive in the note. There were some ramblings in there. It spoke mainly of his intent to burn his neighborhood down and hurt as many people as possible before stopping," Webster police Chief Gerald Pickering said at a press conference on Tuesday morning. Hours later, authorities announced that human remains were found in the charred house that 62-year-old Spengler shared with his 67-year-old sister, Cheryl Spengler. Police said the victim is believed to be the shooter's sister. Police say Spengler armed himself with a revolver, shotgun and military-style rifle before he set his house afire to lure first responders into a pre-dawn death trap on Christmas Eve. Pickering says Spengler "was equipped to go to war." Spengler killed himself as seven houses burned around him. A friend said Spengler hated his sister but police say a motive hasn't been determined. Spengler was armed with a .223-caliber Bushmaster rifle, a .38-caliber revolver and a 12-gauge shotgun, cops said. The Bushmaster rifle used by Spengler is the same make and caliber semiautomatic rifle as the one used in the Connecticut school massacre. Spengler killed two firefighters and wounded two others before fatally shooting himself. Once firefighters arrived, Spengler, under a 'position of cover' fired at the firefighters from a distance after they arrived around 5:30 a.m. to battle the blaze near the Lake Ontario shore, just east of Rochester, Town of Webster Police Chief Gerald Pickering said. Spengler was found around 11 a.m. near the shore of the lake with a self -inflicted gun shot wound. Pickering said there were "heroic acts" by first responders who attempted to bring their comrades under cover from the attack. "It is a very difficult situation," he said Monday at a press conference, holding back tears. The two volunteers who survived were taken to University of Rochester Medical Center were they were listed in guarded condition in the intensive care unit, according to hospital officials. About 100 people attended an impromptu memorial vigil Monday evening in Webster, a suburb of Rochester. Dozens of bouquets were left at the fire station, along with a handwritten sign that said, "Thanks for protecting us. Investigators believe that Spengler set his family's home and a car on fire which spread to six other homes,officials said. According to police officials, Spengler has a lengthy criminal record, including a manslaughter conviction for murdering his own grandmother, Rose Spengler, when he bludgeoned her to death with a hammer in 1980. Spengler Served 17 years in prison for the his crime. He said Spengler "loved his mama to death." The Associated Press and FoxNews.com's Jana Winter and Perry Chiaramonte contributed reporting to this story.