The six people who stole the shipment of highly radioactive cobalt-60 were released from a Mexican hospital but still remain in police custody. All of the six were arrested on Thursday and taken to a hospital in Pachuca for observation and tests.
Mexican officials said that the thieves targeted the cargo truck with a movable platform and crane but were unaware of what they are taking.
Cobalt-60 emits strong gamma rays and pose a significant threat of radiation sickness and skin burns in a short term and causes cancer of the liver, kidneys and bones. The driver of the truck said that two armed men made him get out of the truck, tied his hands and feet and left him in a vacant lot.
The Cobalt-60 thefts triggered alerts in six Mexican states and Mexican city. There were concerns that the material could have been stolen to make a bomb.
The truck was found abandoned about 24 miles away from where it was stolen and the container for the radioactive material was found open.
Hidalgo state Health Minister Pedro Luis Noble said that the six men suffered from dizziness and skin irritations. The atomic energy agency said that the cobalt had an activity of 3,000 curies meaning it was fatal to be close to this amount of unshielded radioactive material for a period of time in range of minutes.
The material belonged to a hospital in northern city of Tijuana and was being transported to nuclear waste facility in the state of Mexico.