The 62-year-old ex-convict who set his house on fire and ambushed firefighters in New York state, killing two, left a chilling note for authorities saying he was doing “what I like doing best, killing people.”

Police from the town of Webster say William Spengler said in a two to three-page typewritten note he wanted to burn his neighborhood down although he did not explain what motivated him to kill.

Officials also said they recovered a revolver, a shotgun and a .233-caliber semiautomatic Bushmaster rifle, which was used to fire the fatal shots. The military-style assault rifle is the same make as the one used December 14 to massacre six teachers and 20 children at the Sandy Hook Elementary School in Newtown, Connecticut.

As a convicted felon, Spengler was not allowed to own firearms.

Police said Spengler took cover before opening fire on the first volunteer firefighters to arrive on on the scene and shot himself after police arrived and returned fire.

Two firefighters were shot but survived the shooting. They were evacuated with the help of an armored personnel carrier.

Spengler served 17 years in prison after being convicted for the beating death of his 92-year-old grandmother. Officials say he shared the house with his sister, who is still missing. Some neighbors have said Spengler did not get along with his sister and that ongoing strife with her might have helped set him off.

Residents of Webster, New York have been marking Christmas with heavy hearts .

Many gathered at a local firehouse on Christmas eve to pay tribute to the dead firefighters. The Associated Press reported a fire department spokesman thanked participants and then asked them to go home and spend the holiday with their families.

The deadly shooting in New York state was just one of several that made national headlines Monday.

A police officer in Houston, Texas was shot and killed in a shootout early Monday and a police officer in a suburb of Milwaukee, Wisconsin was found dead Monday. Officials say she had been shot several times.

The rash of shootings slightly more than a week after 20 children and six teachers were killed in Connecticut jolted the nation as many were preparing to celebrate the Christmas holiday.

New York Governor Andrew Cuomo issued a statement Monday calling the shooting in Webster “horrific,” saying “We as the community of New York mourn their loss as now two more families must spend the holidays without their loved ones.”

The Connecticut shooting had already sparked an intense national debate over laws to regulate guns and an examination of the U.S. approach to mental health issues. Some gun-control advocates say Monday's shootings give the issue added urgency.