New Hampshire state and federal authorities investigating the scene where a police officer was fatally shot say a fire that triggered an explosion in the house was intentionally set.
New Hampshire State Police and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives officials also say they've completed their investigation into the death of Brentwood Officer Stephen Arkell.
Arkell was fatally shot last week after he arrived at a home in Brentwood to respond to a reported domestic dispute. Police say the shooter, 47-year-old Michael Nolan, was killed as well.
Authorities say the house was set on fire in several locations, and that the fire overwhelmed a sprinkler system before mixing with leaking propane to cause the explosion. The leak was attributed to bullets hitting the gas line.