The deaths of two Mexicans had earlier been confirmed, bringing the total number of Mexicans killed to eight.
Six other Mexicans were injured in the attack. There 14 or 15 Mexicans who traveling on a desert oasis tour at the time.
Egyptian forces hunting militants in the country's western desert mistakenly opened fire on several vehicles used by Mexican tourists, killing 12 people on Sunday.
The other dead are believed to be Egyptians.