Photo: The Canadian Press. All rights reserved.

A house burns Monday, Dec. 24, 2012 in Webster, New York. A former convict set a house and car ablaze in his lakeside New York state neighbourhood to lure firefighters then opened fire on them, killing two and engaging police in a shootout before killing himself while several homes burned. Authorities used an armoured vehicle to evacuate the area. (AP Photo/Democrat & Chronicle, Jamie Germano)

A former convict set a house and car ablaze in his lakeside New York state neighbourhood to lure firefighters then opened fire on them, killing two and engaging police in a shootout before killing himself while several homes burned. Authorities used an armoured vehicle to evacuate the area.

Police didn't immediately know a motive. They said the gunman's sister was unaccounted for.

Police said the gunman, 62-year-old William Spengler, shot at the arriving firefighters, probably with a rifle from atop an earthen berm.

"It does appear it was a trap," town Police Chief Gerald Pickering told a news conference. "These people get up in the middle of the night to go put out fires. They don't expect to be shot and killed."

William Spengler had served more than 17 years in prison for beating his 92-year-old grandmother to death in 1980 at the house next to where Monday's attack happened, Pickering said. Spengler was paroled in 1998 and had led a quiet life since, authorities said. He lived with his 67-year-old sister, Cheryl Spengler, and mother, Arline, who died in October.

A friend said William Spengler didn't seem violent but "couldn't stand" the sister who lived with him. Roger Vercruysse said Spengler "loved his mama to death." He said he thinks Spengler "went crazy" after she died in October.

Two firefighters died at the scene Monday, and two were hospitalized. A fifth man who was passing by was also injured.

Two of the firefighters arrived on a fire engine and two in their own vehicles, Pickering said. After the gunman fired, one of the wounded men managed to flee, but the other three couldn't because of flying gunfire.

Emergency radio communications captured someone saying he "could see the muzzle flash coming at me." The audio posted on the website RadioReference.com has someone reporting "firefighters are down" and saying "got to be rifle or shotgun."

The first Webster police officer who arrived chased Spengler and exchanged gunfire with him, authorities said.

The officer "in all likelihood saved many lives," Pickering said.

Seven houses were destroyed, Pickering said, and police have not been able to get inside them to determine if there are any more victims.

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 an emergency dispatcher, whose age was not released.

Pickering described Chiapperini as a "lifetime firefighter" with nearly 20 years with the department, and called Kaczowka a "tremendous young man."

The two wounded firefighters, Joseph Hofstetter and Theodore Scardino, were in guarded condition, authorities said. Both were awake and alert and are expected to recover. Hofstetter was hit once in the pelvis, and the bullet lodged in his spine, authorities said. Scardino was hit in the chest and knee.

Grieving firefighters declined to talk to reporters. At an impromptu memorial vigil Monday evening, about 100 people stood in the cold night air, some holding candles.