Suspicious letters sent to US senators and election offices under investigation

US federal authorities are investigating a series of letters containing suspicious substances that were sent to congressional offices and state election offices across the country. The FBI and the US Postal Inspection Service said they were working to trace the source of the mailings, noting that some of the letters were intercepted before they reached their intended recipients.

Officials have not disclosed how many offices were targeted in total, though several secretaries of state and congressional offices confirmed they had received the letters. The incident comes just weeks ahead of the US midterm elections and follows previous security scares involving suspicious mail sent to public officials.

At least five Democratic senators' offices were sent the letters, with most intercepted before delivery. These included the offices of California Senator Alex Padilla, Connecticut Senator Chris Murphy and New York Senator Kirsten Gillibrand, according to confirmations given to the BBC by the senators' offices. US broadcaster CBS News, a BBC partner, reported that New York Senator Chuck Schumer and Delaware Senator Lisa Blunt Rochester also received similar mail.

Padilla issued a statement to the BBC describing the episode as a reminder of the serious risks faced by public officials and election administrators amid increasingly hostile political rhetoric.