Police officers are seen standing guard outside a local pharmacy in Amesbury, nine miles north of Salisbury, southern England, on July 4, 2018 where two people were found unconcious at a residence in Amesbury in circumstances that caused a major incident to be declared were believed to have visited. 
Two people have been hospitalised in a critical condition for exposure to an &quot;unknown substance&quot; in the same British city where former Russian spy Sergei Skripal and his daughter were poisoned with a nerve agent earlier this year. British police declared a &quot;major incident&quot; after the couple, a man and a woman in their 40s, were discovered unconscious at a house in a quiet, newly-built area in Amesbury, with a number of locations cordoned off by police.
 / AFP PHOTO / Geoff CADDICK