Two US volunteer firefighters have been shot dead and two injured while responding to an emergency call in the town of Webster in New York state, US media reported on Tuesday.
Police said the four were fired upon in an “apparent trap” as they arrived late Monday.
The blaze broke out just before and officers had to evacuate nearby residents in an armoured car.
A gunman was later found dead at the scene, the police said.
The man was 62-year-old William Spengler, Webster Police Chief Gerald Pickering told media.
Spengler appeared to have shot himself in the head, Mr Pickering said.
He had previously served a 17-year jail sentence after being convicted of killing his grandmother.
Spengler’s sister is unaccounted for and police fear she may have died in the fire, which engulfed seven houses.
The two dead firefighters were named by police as Tomasz Kaczowka and Mike Chiapperini.
Pickering told reporters: “It does appear it was a trap.
“These people get up in the middle of the night to go put out fires; they don’t expect to be shot and killed.”
The two injured firefighters were named as Joseph Hofsetter and Theodore Scardino.
They are being treated for gunshot wounds at the Strong Memorial Hospital and are expected to recover.
Another passer-by was also injured in the shooting.
Police spokesmen said the area was “an active crime scene” but that no more shooters were believed to be present.
Roger Vercruysse, described as a friend of William Spengler, was quoted by the Associated Press as saying that the shooter “couldn’t stand” his sister, who lived with him.
Mr Vercruysse said that Mr Spengler “loved his mama to death”, adding that he “went crazy” after she died in October.