This is shameful, i must admit. However, i'm surprised that you blame solely the French and not the actual murderers of the Harkis and criminals against humaity, the Algerian FLN (who btw murdered much more Algerians than French, and civilians than soldiers).
The massacres started because one hundred european Algerians were killed first. Of course, the reaction was savage and completely disproportionate, i do not deny this, but i just wanted to mention a fact that has been (as often) ignored.
If we need to know what preceded Sétif massacres, we need to know that thousands of Algerians engaged themselves to French army and liberated France, together will all French forces. Many of them were sent to France to liberate a "motherhood" that had never seen and left their lives in Monte Cassino, Italy and in whole France. They fought village to village, and there are even statues in some villages in France commemorating the sacrifice of "Indigènes".
And, when those Algerians dared to ask for independence, Massacres of Sétif was the only answer that France had to them. And this is shame, coward and racism.
So, let us not forget that French colonial army thought that those Algerians were worthy only to fight against Nazism but not to fight for their own liberty. Fortunately, History denied French colonialism.
So, you are wrong. Massacres of Sétif did not start because Algerians were killing French. Before the 8th of May 1945, Algerians were fighting to liberate France from Nazism.
And a detail: the massacre in Sétif started when one 20-year old Algerian refused to relpy the Algerian flag. He was killed imediately and the colonial army (including Harkis) started a massacre during which 27 French died and, according to France even, 8,000 - 10,000 Algerians. There is nothing to add to that kind of crimes.