A police cordon in Salisbury has been lifted after tests confirmed a man taken to hospital had not come into contact with Novichok.
Emergency services were called at 6.20pm on Thursday to the scene near Zizzi restaurant, where Sergei and Yulia Skripal had lunch before they fell ill.
Wiltshire Police said they were “taking highly precautionary measures” in dealing with the incident involving a man in his 30s because of the ongoing situation in the city and nearby Amesbury, in Wiltshire.
But after the section of Castle Street was reopened on Thursday night, the force said: “We can now confirm that there is no concern for either his health or any wider risk to the public.
“We understand that our initial response to the incident may have looked alarming, but we hope you appreciate why we needed to take this highly precautionary measure.”
A Salisbury District Hospital spokesman said tests to determine if he came into contact with any nerve agent came back negative, as did tests on members of the public.
An eyewitness, who asked not to be named, told the Press Association the man involved was a “local homeless guy” who was “sat on the floor, completely conscious, talking”.
He said he saw a paramedic at the scene climbing into a chemical suit while another “was shouting at the man to stay put and stay on the floor”.
“All the police officers had rubber gloves on,” he added.
Publisher George Walkley, 41, arrived on the scene at around 8pm.
He said: “I was walking through the city centre and saw emergency vehicles and they had sealed off a stretch of Castle Street in Salisbury.
“There was a very heavy police presence there along with the fire service and ambulances.
“Just inside that cordon between Zizzi and Tesco they had a green tent thing set up.”
The Skripals ate at the restaurant shortly before they were found unconscious on a nearby bench on March 4 after being poisoned with Novichok.
Charlie Rowley, 45, remains seriously ill in hospital, and his partner Dawn Sturgess, 44, died after the pair collapsed at his home in Amesbury, on June 30, having been exposed to the nerve agent.