An upstate New York woman was arrested Friday and hit with federal and state charges connected to the fatal shootings of two volunteer firefighters on Christmas Eve.The woman, Dawn Nguyen, 24, was charged with knowingly making a false statement in the purchase of guns in connection with the weapons used in the slayings, U.S. Attorney William Hochul told a news conference Friday. She was charged earlier on a state violation of filing a falsified business record.Hochul said Nguyen bought the guns on behalf of William Spengler, 62, who allegedly shot four firefighters responding to a fire he had started in his home on Monday outside Rochester, N.Y., killing two of them, before killing himself.