U.K. police say 2 more people exposed to Novichok nerve agent

The same nerve agent that recently poisoned a former Russian spy and his daughter in the U.K. has left another two people in critical condition, according to British counterterrorism police. 

The latest poisoning, with the nerve agent Novichok, occurred just a few kilometres from that of Sergei and Yulia Skripal. It's not yet clear if the poisoning was intentional or an accident.

The Wiltshire police force declared a "major incident" on Wednesday, several days after a man and a woman in their 40s were hospitalized after being found unconscious at a residential building in Amesbury, 13 kilometres from Salisbury, where the Skripals were poisoned on March 4.

The pair were initially found Saturday evening, with the woman being taken to hospital first. Hours later, ambulances returned to the same home and took the man to hospital. The initial belief was that the pair had been sickened by taking a batch of contaminated drugs, but by Monday concerns over symptoms had mounted to the point where samples from both patients were sent to Porton Down, a military research centre.

Police said they received test results Wednesday night that showed the pair had been exposed to Novichok.

At this stage, nobody else has appeared with similar symptoms, police said. Police haven't determined the means of transmission, saying about 100 counterterrorism detectives are working with local police to try and determine how the pair were exposed.

The local police urged people to be patient as the investigation, which is now being led by counterterror officers, proceeds. Buildings will be cordoned off and people will see officers in protective equipment carry out their work.

Nerve agents, which are typically inhaled or absorbed through the skin, block an enzyme that controls communication between nerve cells and muscles, which then causes muscles and glands to be overstimulated. That results in symptoms including contracted pupils, vomiting, breathing difficulties and convulsing muscles.

"We have cordoned off a number of sites in the Amesbury and Salisbury areas that we believe the two individuals visited in the period before they fell ill," said Neil Basu, Scotland Yard's assistant commissioner for counterterrorism.

"This is a precautionary measure while we continue to investigate how they came into contact with the substance."

Both victims are British nationals, Wiltshire police deputy chief Const. Paul Mills said earlier in the day.

He did not release their names, but friends named the couple as Dawn Sturgess, 44, and Charlie Rowley, 45 — though the names were not confirmed by counterterrorism police.

A statement from the Wiltshire Police released late Wednesday cited a local public health official as saying that, based on the small number of cases, there is "no significant health risk to the wider public." That assessment will be reviewed as new information emerges, said Mike Wade, the deputy director of health protection for the area where the latest case unfolded.

The poisoning of the Skripals sparked a diplomatic row as the U.K. said some evidence in the Skripal case suggested the attack was carried out at the behest of Russia, and British media reported in April that the agent was traced to a Russian military facility.

The British government eventually moved to expel Russian diplomats, and Russia, which insists it is not to blame in the Skripal case, retaliated and kicked out dozens of British officials.

Police did not point to any individuals or nations in the more recent case, with Basu saying "we are not in a position to say whether the nerve agent was from the same batch that the Skripals were exposed to."

He said investigators will be exploring whether the two cases are linked.

"It is important, however, that the investigation is led by the evidence available and the facts alone and we don't make any assumptions."