A police officer stands outside Amesbury Baptist Centre where British police have declared a "major incident" after two people were exposed to an unknown substance. (Photo: AP)

London (People's Daily) - Two people are in critical condition after they were exposed to an “unknown substance” that locals fear could be the same nerve agent used on Sergei Skripal and his daughter months ago.

As various theories have emerged, authorities were unable to confirm if the couple had possibly come into contact with residue from novichok, the same nerve agent used on the Skripals. 

Tests are underway, and authorities are waiting for the lab results before making an announcement. 

The day before their symptoms emerged, Charlie Rowley and Dawn Sturgess were in Queen Elizabeth Park, about a five-minute walk from where the Skripals were found unconscious.  

A counter-terrorism group joined the investigation Wednesday morning. 

At a press conference in Amesbury, authorities said the couple first became sick on Saturday and it was believed that they may have been using drugs from a “contaminated batch.”