Lightning striking a tree caused tourists to scatter Monday at Chichen Itza, prompting some to think someone had exploded a bomb.

Yucatan, normally immune to the narcos who commit violence throughout Mexico, got its first taste last month when 11 decapitated bodies were found in the outskirts of the state’s capitol, Merida. The victims had been involved in the drug trade and were believed to have been murdered by a rival drug gang.

Since then, there has been a certain level of anxiety among the populace. When lightning hit a tree at Chichen during the bi-annual equinox observance, some believed it to be a bomb. Only a few days before, narcos had tossed a grenade into a crowd in another state, killing women and children.

This time it was only lightning, but one man was injured. Agustín Perera, who sells trinkets to tourists, was standing under the tree when it was struck. He suffered burns on one side of his body and had to be taken away by ambulance. Two tourists suffered “nervous shock,” according to authorities.

The event kicked off several days of equinox observance that would be ruined by rain. Without sun, the light-and-shadow effect of Kukulcan crawling down the side of El Castillo, the pyramid, could not be seen.