A shooting at former US president Donald Trump’s rally is being treated as an “assassination attempt,” the FBI says. Trump was escorted to safety by Secret Service agents after gunshots were heard during the rally in Pennsylvania on Saturday. Writing on his social media site Truth Social after the incident, Trump said a bullet had pierced the upper part of his right ear. Special agent in charge of the FBI’s Pittsburgh field office Kevin Rojek said authorities had not yet identified a motive. “This evening, we had what we’re calling an assassination attempt against our former president Donald T…