What is the correct Islamic action for a family whose homes have been attacked, after the assault, and are the killer and the killed in Hellfire if any individual from either family is killed or injured as a result of this fighting?

Allah has legislated for the Muslim the right to repel aggression and remove injustice. The correct action in the event of aggression is to bring the grievance to the ruler (Wali al-Amr), who is obligated to repel the aggressor, exact retribution from him, give justice to the wronged, and reconcile everyone. Allah Almighty said: "And if two factions among the believers should fight, then make settlement between the two. But if one of them oppresses the other, then fight against the one that oppresses until it returns to the ordinance of Allah. And if it returns, then make settlement between them with justice and act equitably. Indeed, Allah loves those who act equitably." The Prophet, peace and blessings be upon him, warned against discord (fitan) and fighting in it, for "If two Muslims meet with their swords, the killer and the killed are in the Hellfire," because the killed was eager to kill his companion.