A powerful earthquake shook a broad swath of Mexico, including the capital Mexico City, on Monday.

The magnitude 7.7 earthquake with an epicenter in the state of Michoacan shook southwestern Mexico, according to the country’s seismology service.

That came shortly after residents of Mexico City took part in a massive readiness drill, one that doubled as a commemoration of the catastrophic 1985 and 2017 quakes that occurred on the same date. Those disasters killed thousands and hundreds respectively.

Early reports suggested that Monday’s incident would have a much smaller toll. Mexico’s President Andrés Manuel López Obrador reported one death when a wall collapsed at a shopping center in the port city of Manzanillo, Colima.