Home Secretary Amber Rudd is in Salisbury on Friday following the attack on Sergei Skripal and his daughter, who were found slumped on a park bench. Both remain in critical condition at a local hospital.
The U.K. has vowed to take strong action against whoever was responsible for the "brazen and reckless" attack.
Wiltshire County police say that "around 21 people," including the Skripals, have received treatment following the attack. But British health authorities say there is little risk to the wider public.
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