The FBI has joined the investigation into the violent death of a New Hampshire police officer.  Officials say Brentwood police officer Steve Arkell was shot and killed just before a house exploded into a ball of flames on Monday.

He was responding to a domestic disturbance at the time.  It's believed Arkell was shot by a man named Michael Nolan, who died inside the home.  A second officer tried to enter but was driven out by gunfire.

Witnesses say the whole thing started late yesterday afternoon with an argument between an elderly man and his adult son, thought to be Michael Nolan.