“The passengers jumped from the balloon,” the government of the state of Mexico said in a statement, adding that a child suffered burns.
It identified the victims as a 39-year-old woman and a 50-year-old man, without providing their names. It said the minor had suffered second-degree burns to the face as well as a fracture of the right femur.
It did not say whether there were any other passengers on the balloon.
A video posted on social media shows the balloon’s gondola on fire, in a perfectly clear sky.
Several tour operators offer balloon flights over Teotihuacan, some 45 miles (70 kilometers) northeast of Mexico City, for around $150.
With its Pyramids of the Sun and the Moon, and its Avenue of the Dead, Teotihuacan is a popular tourist destination, a surviving monument to the pre-Columbian period.