Motive a mystery in firefighter ambush, shootings WEBSTER, N.Y. A man who set his house on fire, then lured firefighters to their deaths in a blaze of flames and bullets had attracted little attention since he got out of prison in the 1990s for killing his grandmother, authorities said. But two months ago, William Spengler's mother died, leaving the 62-year-old ex-con in a Lake Ontario house with his sister, who he "couldn't stand," a friend said. Webster, N.Y. firefighter tragedy Spengler set a car and a house in his neighborhood ablaze early Monday, luring firefighters to the neighborhood and then killed two, wounded two others and injured a police officer while several homes burned around him, police said. Spengler then killed himself. His sister, Cheryl, was missing. Spengler's motive was still unclear, authorities said. 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. Flags already at half-staff at the Webster firehouse for the victims of the Newtown shooting will now stay that way for the town's late firefighters, reports CBS News correspondent Jim Axelrod. An undated photo of William Spengler / Monroe County Sheriff's Office Spengler had been living in the home in Webster, a suburb of Rochester, with his mother and sister since his parole in 1998. He had served 17 years in prison after the beating death of his 92-year-old grandmother in 1980, for which he had originally been charged with murder but pleaded guilty to a reduced charge of manslaughter. His mother, Arline, died in October. On Monday, Spengler fired at the four firefighters when they arrived shortly after 5:30 a.m. at the blaze, town police Chief Gerald Pickering said. The first police officer who arrived chased the gunman and exchanged shots. Spengler lay in wait outdoors for the firefighters' arrival, then opened fire, probably with a rifle and from atop an earthen berm, Pickering said. "It does appear it was a trap," he said. Authorities used an armored vehicle to help residents flee dozens of homes on the shore of Lake Ontario a day before Christmas. Police restricted access to the neighborhood, and officials said it was unclear whether there were other bodies in the seven houses left to burn. Authorities said Spengler hadn't done anything to bring himself to their attention since his parole. As a convicted felon, he wasn't allowed to possess weapons. Monroe County District Attorney Sandra Doorley said Spengler led a very quiet life after he got out of prison. A friend said Spengler hated his sister. Roger Vercruysse lived next door to Spengler and recalled a man who doted on his mother, whose obituary suggested contributions to the West Webster Fire Department. "He loved his mama to death," said Vercruysse, who last saw his friend about six months ago. Vercruysse also said Spengler "couldn't stand his sister" and "stayed on one side of the house and she stayed on the other." Emergency radio communications capture someone saying he "could see the muzzle flash coming at me" as Spengler carried out his ambush. The audio posted on the website RadioReference.com has someone reporting "firefighters are down" and saying "got to be rifle or shotgun -- high powered ... semi or fully auto." After Spengler fired, one of the wounded men fled, but the other three couldn't because of flying gunfire. The police officer who exchanged gunfire with Spengler "in all likelihood saved many lives," Pickering said. A police armored vehicle was used to recover two men, and eventually it removed 33 people from nearby homes, the police chief said. The dead men were identified as police Lt. Michael Chiapperini, 43, the Webster Police Department's public information officer; and 19-year-old Tomasz Kaczowka, also a 911 dispatcher. Pickering described Chiapperini as a "lifetime firefighter" with nearly 20 years in the department, and he called Kaczowka a "tremendous young man." Kaczowka's brother, reached at the family home Monday night, said he didn't want to talk. The two wounded firefighters, Joseph Hofstetter and Theodore Scardino, remained in guarded condition Tuesday at Strong Memorial Hospital, authorities said. Hofstetter, also a full-timer with the Rochester Fire Department, was hit once in the pelvis, and the bullet lodged in his spine, authorities said. At West Webster Fire Station 1, there were at least 20 bouquets on a bench in front and a bouquet of roses with three gold-and-white ribbons saying, "May they rest in peace," "In the line of duty" and "In memory of our fallen brothers." A handwritten sign says, "Thanks for protecting us, RIP." Two candles were lit to honor the dead. Grieving firefighters declined to talk to reporters. At the impromptu memorial vigil Monday evening, about 100 people stood in the cold night air, some holding candles. A fire department spokesman made a brief appearance, thanked them all and told them to go home and appreciate their families. Cathy Bartlett was there with her teenage son, who was good friends with Kaczowka. Bartlett's husband, Mark Bartlett, has been a firefighter there for 25 years but missed the call this morning. "Thank God my husband slept through the first alarm and didn't get up until the second one went off," she said. The shooting and fires were in a neighborhood of seasonal and year-round homes set close together across the road from the lakeshore. "It's sad to see that this is becoming more commonplace in communities across the nation," O'Flynn said. Gov. Andrew Cuomo said the State Police and Office of Emergency Management were working with local authorities. "Volunteer firefighters and police officers were injured and two were taken from us as they once again answered the call of duty," Cuomo said in a statement. We as the community of New York mourn their loss as now two more families must spend the holidays without their loved ones.