A man has been arrested in connection with three letters sent to US officials, including President Barack Obama, which are suspected of containing poisonous ricin.
The FBI said Paul Kevin Curtis, a 45-year-old from Corinth, Mississippi, is "believed to be responsible for the mailings of the three letters sent through the US Postal Inspection Service."
The letters, "which contained a granular substance that preliminarily tested positive for ricin" were addressed to a Republican senator, the White House and a Mississippi justice official, the FBI said.
More top news
After a mild start temperatures should pick up, with the south of England seeing highs of 26C.
In Edinburgh tonight you can hear it and feel it. The buzz, the banter of the day and the thrilling sense something big is coming tomorrow.
There is nervousness, anxiety and on the streets of Edinburgh fuelled by an atmosphere unlike anything seen before in recent UK politics.