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.
The gunman, 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, town Police Chief Gerald Pickering said. Spengler, 62, was paroled in 1998 and had led a quiet life since, authorities said. Convicted felons are not allowed to possess weapons.
Police say he set the fires to lure firefighters to his home and then opened fire from outdoors, probably with a rifle from atop an earthen berm.
"It does appear it was a trap," 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."
Police didn't immediately know a motive. They said Spengler's 67-year-old sister, Cheryl Spengler, was unaccounted for. He lived in the house with his sister and mother, Arline, who died in October.
Two firefighters died at the scene, and two were hospitalised. 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.
A police armoured vehicle was used to recover two of the men, and eventually it evacuated 33 people from nearby homes, the police chief said.
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 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 Hofsetter and Theodore Scardino, were in guarded condition, authorities said. Both were awake and alert and are expected to recover. Hofsetter was hit once in the pelvis, and the bullet lodged in his spine, authorities said. Scardino was hit in the chest and knee.
The neighbourhood is popular with recreational boaters but is normally quiet this time of year.
"We have very few calls for service in that location," Pickering said. "Webster is a tremendous community. We are a safe community, and to have a tragedy befall us like this is just horrendous."
Monroe County Sheriff Patrick O'Flynn lamented the violence, which comes on the heels of other shootings including the massacre of 20 students and six adults at a school in Newtown, Connecticut.
"It's sad to see that that this is becoming more commonplace in communities across the nation," O'Flynn said.
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