Monroe County Sheriff's Office via NBC News
Undated booking photo of William Spengler, who shot and killed two firefighters Monday.
By Jason White, NBC News
The gunman who ambushed four volunteer firefighters, killing two, in upstate New York had spent 17 years in prison for beating his grandmother to death with a hammer in 1980, police said.
William Spengler opened fire on the volunteers as they responded to a blaze just before 6 a.m. ET in a small cluster of homes along Lake Ontario in Webster, N.Y., police said, rocking this close-knit community.
The 62-year-old convicted felon had apparently set a trap, firing on the first responders from atop an earthen berm.
"It does appear that it was a trap that was set," said Webster Police Chief Gerald Pickering, his voice breaking at times. "People who get up in the middle of the night to fight fires, they don't expected to get shot and killed."
Pickering lost a colleague in the incident: Police Lieutenant Michael Chiapperini, who was a volunteer firefighter. The other firefighter killed by Spengler was Tomasz Kaczowka.
Despite being shot, one of the injured firefighters was able to flee from scene under his own power. But the others remained pinned down on the narrow strip of land between Lake Ontario and Irondequoit Bay until a SWAT team arrived.
As police closed in, Spengler took his own life with a gunshot wound to the head, Pickering said. He was convicted of manslaughter in 1981 after the death of his grandmother, Rose Spengler, and was paroled in 1998.
Spengler's 67-year-old sister Cheryl Spengler is unaccounted for, Pickering said. Spengler lived in the house with his sister and mother, Arline, who died in October.
Prior to Monday's shooting, Webster police had not had any run-ins with Spengler since he was paroled, they said.
Police would not say what kinds of guns Spengler used, but as a convicted felon, he could not legally own firearms.
The two injured firefighters, Theodore Scardino and Joseph Hofstetter, were being treated for "significant injuries," according to Dr. Nicole Stassen, a surgeon at the University of Rochester Medical Center. She said both were awake and alert, however, and not on ventilators.
An off-duty police officer was also injured when he was hit by shrapnel after his car took bullets to the windshield and engine block, according to the Rochester Democrat and Chronicle. His condition is unclear at this time.
After the shooting, the fire grew to engulf at seven homes and one motor vehicle.
"These firemen are part of our family. You go into a fire with these guys. To see them go down with something like this is totally unexpected. We are in shock," Billy Gross, fire commissioner for West Webster, told the Democrat and Chronicle.
Dozens of area residents were evacuated, with police searching them as they left, the newspaper reported.
"Miserable thing to happen this time of year," Mark Johns, a state assemblyman who represents the area, told local NBC station WHEC. Johns said he knew some of the firefighters who were shot.
New York Gov. Andrew Cuomo issued a statement after the shooting, offering his "deepest condolences."
"All of our thoughts and prayers go to the families and friends of those who were killed in this senseless act of violence," Cuomo said. "New York's first responders are true heroes as they time and again selflessly rush toward danger in order to keep our families and communities safe."
NBC's Tom Winter and Rosanna Arlia contributed to this report.