(Image source: YNN ) BY NATHAN GIANNINI ANCHOR ZACH TOOMBS   The man accused of shooting and killing two firefighters in upstate New York has been identified as convicted killer William Spengler.   According to the Huffington Post, 62-year-old Spengler was convicted of manslaughter in the death of his grandmother in the early 1980s. He served 17 years in prison before being released on parole in 1998. “ He was found dead of a self-inflicted gunshot wound after the violence at the fire this morning.”   Four firefighters responded to the fire in Webster, New York at around 5:30 Monday morning. Your News Now reports -- police believe Spengler intentionally started the fire...       “...as part of a plan to ambush firefighters. When they arrived on the scene of the early morning fire, officers say Spengler opened fire. Firefighters Mike Chiapperini and Tomasz Kaczowka were both killed.”   Two other firefighters and an off-duty police officer were injured. The first police officer who arrived on the scene reportedly chased and exchanged gunfire with Spengler.   In a press conference, the town’s police chief told the media, the firefighters who died were both volunteers.    “These people get up in the middle of the night to go put out fires. They don’t expect to be shot and killed.”   According to the Associated Press , Spengler’s sister Cheryl is currently unaccounted for. It’s believed they lived together in the house that was set on fire.    Seven homes were reportedly destroyed in the blaze, which is now under control.    SOC