ROCHESTER, N.Y. (AP) — A New York woman was sentenced to eight years in federal prison Wednesday for supplying guns to a former neighbor who used them to kill his sister and two firefighters in a Christmas Eve ambush that also caused seven homes to burn to the ground.

Dawn Nguyen, 25, pleaded guilty in June to three felonies, including supplying guns to a known felon. Before her sentencing, she apologized to firefighters and others in the courtroom and asked for forgiveness.

The sentence is much harsher than the eight- to 14-month prison term suggested by federal sentencing guidelines.

U.S. Magistrate David Larimer said it was justified because Nguyen knew that William Spengler, 62, had served time in prison for bludgeoning his grandmother to death with a hammer in 1981 and had said he would kill again.

“You know someone was involved in the death of their grandmother. That alone should raise not one but 100 red flags,” Larimer said in the courtroom crowded with members of the slain firefighters’ West Webster Fire Department and other first responders. “Maybe this is not the kind of person you want to provide with guns.”

Prosecutors said Nguyen accepted $1,000 from Spengler to go with him to a Gander Mountain store in June 2010 and buy a semi-automatic rifle and pistol-grip shotgun, lying on a form that they were for her.

More than two years later, the weapons were found Dec. 24, 2012, near Spengler’s body following the ambush that killed volunteer firefighters Tomasz Kaczowka and Michael Chiapperini. Spengler committed suicide.

Nguyen’s attorney, Matthew Parrinello, said Nguyen believed Spengler wanted the weapons for hunting and could not have predicted what he would do.

“This was a quirky, weird, crazy neighbor that she knew, but he was nice and kind and he did things for her family,” Parrinello, said. “He never gave her any indication prior to her purchasing the weapons that he was going to do anything violent.”

Nguyen, who was a college student at the time, turned around to address the firefighters before hearing her sentence, telling them she is haunted by what happened.

“I’m so, so sorry,” she said to the group, which included Theodore Scardino and Joseph Hofstetter, who were wounded by Spengler as they responded to the home he shared with his 67-year-old sister, Cheryl. “I’m sorry for the people whose lives have been affected.”

Because of the gunfire, firefighters could not extinguish the fire, leaving it to spread and destroy six additional homes in the Lake Ontario community. Cheryl Spengler’s body was found in the ashes. She had been shot in the head.

Nguyen’s federal prison sentence will run concurrent with a 1 1/3- to 4-year sentence she began serving earlier this year on related state charges.

“There is nothing that happened in court here today that will bring back the deceased firefighters who died trying to save the community on Christmas Eve, nor relieve the pain that the families will continue to suffer, not only every holiday season, but day in and day out as they continue to live with the consequences that this defendant, Dawn Nguyen, started in 2010,” U.S. Attorney William Hochul said outside the courthouse, where he had sought a 10-year sentence.

West Webster Fire Department spokesman Al Sienkiewicz was unmoved by Nguyen’s apology.

“You’re at that point in time when you say whatever you can say to save yourself,” he said.