No verified count exists. On the French side, Saulay (1983) gives two daily tolls from operation reports (23 February: 22 killed; 28 February: 64 killed and 115 wounded); Hart counts ten officers killed; Qaid ʿAli puts forward 3,500 casualties, mostly among Moroccan troops and partisans.
On the Aït Atta side, estimates vary sixfold: 327 dead including 117 women (Benadada, after a 1987 Moroccan book not consulted, which Wikipedia miscopies as “127 women”); 1,300 casualties according to Qaid ʿAli, Assou's son (Hart, 1984), killed and wounded; over 2,000 killed, including 500 armed men, according to a calculation by General Huré (estimated refugees minus people who came over), translated by Hart. Arabic Wikipedia's 1,300 “martyrs” matches Qaid ʿAli's figure, which does not refer only to the dead. English Wikipedia's 4,000 civilian victims rest on no verifiable source.
All sources agree on the severity: officers acknowledge that the defenders' losses were “much heavier” than their own, Huré estimates that 90% of the livestock died or was raided, and Hart reports that women were killed while fetching water, including a thirteen-year-old daughter of Assou. The lack of an established figure is not a lack of victims.