The crack allowed 6,000 cubic meters (about 1.5 million gallons) per second of wastewater to flow out of the canal into the San Isidro and La Providencia residential areas, the state-run news agency Notimex reported.
No injuries were reported.
Crews and machinery reached the site about 1:30 p.m. to begin repairs.
The spill caused officials to close the Mexico-Puebla Highway in the area, Notimex said.
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