On the morning of November 14, 1921, Luciano Pérez Carpio — a secret-police employee of the Álvaro Obregón government, then engaged in the anti-clerical measures that would erupt into the Cristero War four years later — deposited a bouquet of flowers containing twenty-nine sticks of dynamite at the foot of the high altar of the Basilica of Guadalupe in the old sanctuary at Tepeyac.
The bomb detonated during Mass at 10:30 a.m. The blast wrecked the marble steps of the altar, blew out most of the stained-glass windows in the sanctuary, and violently bent the heavy bronze crucifix that stood on the altar — the crucifix is now bent nearly ninety degrees at the shoulders of the corpus. Every pane of glass in the immediate vicinity shattered.
The pane of glass directly protecting the tilma of Guadalupe, four meters above the altar, was untouched. The tilma itself — the cloak of St. Juan Diego bearing the image left in 1531 — showed no damage of any kind. The bent bronze crucifix is preserved in a glass case at the modern basilica, dedicated 1976, as a memorial of the 'Cristo del Atentado' (the Christ of the Attack).