This image shows a piece of machinery that is part of the cargo of a stolen truck.

A United Nations vehicle carrying radioactive materials was stolen in Mexico Monday while traveling to a radioactive waste storage center from the northern city of Tijuana.

The International Atomic Energy Agency has said the truck was carrying cobalt 60, which is used as part of radiotherapy cancer treatments. The heist happened in Tepojaco, and the IAEA said the substance is "extremely dangerous" if removed from its protective shielding or damaged.

The truck was found later on Wednesday close to the place where it was stolen in Mexico, said the Director of the National Commission of Nuclear Safety and Safeguards Juan Eibenschutz. He said the container the truck was carrying was empty.

Eibenschutz said about a half-mile from where the stolen truck was found the cobalt 60 was discovered. He also said there is no risk so far to the surrounding population.