The head of the national civil defense office, Luis Felipe Puente, said Tuesday the trucks and their cargo were stolen in Guanajuato state and later recovered in Hidalgo. Puente said the material, Iridium-192 used in industrial radiography, could have been dangerous if the containers were opened.

Puente was initially holding the news conference to alert the public to the theft, but before he finished word arrived that the trucks had been located.