Pupils were spooked when a bone-filled “child graveyard” was discovered underneath their primary school.
The eerie burial ground was chanced upon as a pit was excavated during renovation works.
The skeletal remains of eight children and one adult were found in the 80sq cm cavity.
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The only complete skeleton – that of a child in early infancy – was found in a wooden coffin measuring 80 by 35 cm.
The casket was decorated with blue, diamond-shaped engravings, and the well-preserved remains were wrapped in a brown shroud.
The feet were pointing south-east, which is unusual, since in Catholic tradition, bodies are usually buried facing east.
Experts from Mexico’s National Institute of Anthropology and History (INAH) believe the usual burial rites may have been skipped – though the reason is a mystery
The skeletons are yet to be analysed in detail, but experts believe the children died between the perinatal period and six years of age.
The discovery of a coin dated 1862 suggests the victims were laid to rest in the 19th century, as reported by Need To Know.
Other artefacts recovered from the pit include buttons, cloth scraps, ceramics, metals, and a piece of paper with some text in a strange language.
The building that now houses the primary school in Zacatecas, north-west of Mexico City, was previously a convent and a hospital.
The first stone is believed to have been laid in 1612.
The astonishing haul has been transferred to a museum in neighbouring Guadalupe to be studied comprehensively.
An INAH spokesperson said: “This discovery will contribute to a deeper understanding of the city’s early inhabitants, their burial customs, and its 400-plus years of history.”
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