ArmInfo.Armenian President Armen Sargsyan sent a letter of condolences to the President of Mexico Andres Manuel Lopez Obrador in connection with the explosion of the pipeline thundering in the state of Hidalgo, which caused many casualties."The President of Armenia expresses deep condolences to the President of Mexico and the friendly Mexican people, and wishes the family and friends of the victims endurance, patience and courage," the official press service of the RA President said.