I am not a pacifist. I believe that the Bible (both Hebrew Scriptures and the New Testament) a person to defend one's self and others from life-threatening force1. Any person who has entered an occupied house should be assumed to be a threat to the health of the residents of that house until the theives are dead, have surrendered, or have fled.
In Mr. Beall's case, he appears to have chased after the criminals after they had left the house. Assuming they were not coming back to the house, they were no longer a threat, and Mr. Beall shouldn't have shot.
Personally, I hope that these goons stop before they hurt anyone else, and I hope they stop before some citizen or policeman stops them. However, I would consider their death by self-defense action of a homeowner a better solution than some innocent's death or serious injury in their hands.
1There are times when people are called to be martyrs. That is a direction from the Holy Spirit, and is a bit out of the pervue of this discussion.