Tragedy struck a family in Newton Tuesday afternoon when a woman killed her adult son by backing over him with a vehicle, said a spokeswoman for the Middlesex district attorney’s office. The man was standing behind his mother’s vehicle when she put it into reverse and drove over him, said spokeswoman MaryBeth Long. He was taken to a local hospital and was pronounced dead upon arrival, Long said. A Newton fire official told reporters on the scene that no charges have been filed in the case, but the district attorney is investigating. The identities of both mother and son were not released, and no further details were available late Tuesday night.