An eyewitness says the person involved was a local homeless man
Emergency servies have attended an incident involving a man outside the Zizzi restaurant in Salisbury.
In March Sergei and Yulia visited the same Italian restaurant before becoming seriously ill and it is believed they came into conctact with the deadly nerve agent Novichok.
Castle Street has been closed and Wiltshire Police are investigating.
A spokesperson said: "Given the ongoing incident in Salisbury and Amesbury, we are taking highly precautionary measures to ensure public safety.
"While we do not want people to be alarmed hope you understand the reasons behind this and we will update you when we have any further information.
"At the moment there is nothing to suggest any wider risk to the public and we would ask people to avoid the immediate area and be respectful of the cordon which is in place."
An eyewitness has stated that the man, believed to be in his 30s, was a "local homeless guy" who was "sat on the floor, completely conscious, talking".
A paramedic arrived on the scene in a full chemical suit and told the man to stay on the floor. According to the eyewitness, all the police officers had rubber gloves on.
More to follow.
