LONDON (AP) — British police have declared a "major incident" after two people were exposed to an unknown substance in a town near where a former Russian spy and his daughter were poisoned with nerve agent.

In a statement, Wiltshire police say a man and a woman — both in their 40s — are in critical condition after being found in Amesbury, 8 miles (13 kilometers) from Salisbury, where Sergei and Yulia Skripal were poisoned in March.

Police on Wednesday were cordoning off places the people visited before falling ill, but public health officials say there is not believed to be a wider risk.

They were hospitalized Saturday for suspected drug overdoses.

Britain accuses Russia of poisoning the Skripals with Novichok nerve agent; Moscow denies the allegation.