Here's the report at the Wall Street Journal, which has a rough sketch of the firefight that killed LaVoy Finicum, "Oregon Occupation Leader Ammon Bundy Arrested, One Dead, After Confrontation With FBI":
Law-enforcement officials familiar with the matter said the incident took place as Mr. Bundy and a handful of other leaders were driving to a public event nearby. Agents with the FBI stopped the vehicle, at which point one of the individuals in the vehicle pulled out a weapon, the people familiar with the incident said.The "dead suspect" would be Finicum.
At that point, FBI agents fired. The individual who was brandishing the weapon suffered fatal injuries, officials said. Officials didn’t identify the dead suspect. Another suspect suffered non-life-threatening injuries, these people said. No FBI agents were injured, according to these people...
He'd apparently been talking apocalyptically in recent days, and in an interview with the Oregonian said that the feds were becoming "hardened" and loaded for bear. See, "Just Yesterday, LaVoy Finicum Warned That Feds Had 'Become Hardened', Brandished Rifles (VIDEO)."