By Catherine E. Shoichet and Chuck Johnston
(CNN) -- The suspect in the shooting deaths of two firefighters in upstate New York Monday is William Spengler, 62, who was convicted in 1981 of first-degree manslaughter for killing his grandmother, Webster Police Chief Gerald Pickering said.
Authorities do not know how Spengler, who died of a self-inflicted gunshot wound, obtained the weapon he used in Monday's shooting or why he opened fire, Pickering said.
Four firefighters were shot, two fatally, while responding to a fire in upstate New York on Monday, and investigators believe the suspect had deliberately set a trap to lure them to the scene.
The alleged assailant, who also died, apparently took aim at the firefighters as they arrived at an early morning house and vehicle fire in the Rochester-area town of Webster, Police Chief Gerald Pickering said.
Pickering said two of the firefighters were shot died at the scene. The two injured firefighters were hospitalized in intensive care, officials said. An off-duty police officer passing by the area also sustained shrapnel wounds, Pickering said.
Authorities did not immediately identify the suspect, who Pickering said was found dead at the scene.
"It does appear that it was a trap that was set," said Pickering, who choked back tears as he talked about the firefighters who were killed. One was also a police lieutenant with about 20 years on the force.
The shooting occurred amid a renewed debate over gun control following the elementary school massacre in Newtown, Connecticut, on Dec. 14 that killed 26 people, 20 of them children.
"As you can see, emotions are extremely high," Monroe County Executive Maggie Brooks told reporters. "There's a heightened awareness to this kind of violence in light of what happened in Connecticut, and I just want everyone to remember: It's Christmas Eve. We have first responders, and we have families who are in pain and crisis today and we need to as a community keep them in our thoughts and prayers."
New York Gov. Andrew Cuomo described the Webster shooting as horrific and senseless.
"Volunteer firefighters and police officers were injured and two were taken from us as they once again answered the call of duty," he said in a statement.
Firefighters first arrived at the Webster fire before 6 a.m., said Rob Boutillier, the town's fire marshal.
The gunfire stopped firefighters from working to extinguish the flames and forced police SWAT teams to evacuate homes in the area. By noon, four houses were engulfed by flames.
"It took a while to make it safe ... to put out the fires," Pickering said.
One firefighter escaped from the scene in his own vehicle about an hour after he was shot and was taken to the hospital by an ambulance from another location, Boutillier said.
Another wounded firefighter was conscious and speaking when he was removed from the scene, Boutillier said.
The wounded firefighters were in intensive care Monday at Strong Memorial Hospital in Rochester, New York, officials said.
It was unclear what type of weapon was used in the Webster shooting.
President Barack Obama has set a January deadline for "concrete proposals" to deal with gun violence.
Sen. Dianne Feinstein, D-California, has said she will introduce legislation to reinstate the assault weapons ban that expired in 2004. The White House has said that the president supports that effort.
Speaking to reporters on Friday, the National Rifle Association's president called for more guns in the wake of the mass shooting, proposing putting an armed guard in every U.S. school in order to protect children.
On Sunday, NRA President Wayne LaPierre told NBC's "Meet the Press" that he would not express support for any new gun restrictions, saying most gun laws on the books are currently rarely enforced.
CNN's Jake Carpenter and John Fricke contributed to this report.