Letters with 'suspicious substances' sent to US election offices

Federal authorities say they are investigating "potentially hazardous" letters containing "suspicious substances" that have been sent to congressional and state election offices around the US. The FBI and the US Postal Inspection Service (USPIS) said they were trying to trace the "suspicious mailings", some of which were intercepted before they were received. Authorities declined to say how many offices had been targeted, but several secretaries of state and congressional offices reported receiving the letters. Coming just weeks before the US midterm elections, it echoes previous security scares involving suspicious mail.