AMESBURY: Two people are in hospital in critical condition after exposure to an “unknown substance” in the same British town where a former Russian spy and his daughter were poisoned with a nerve agent earlier this year, officials said today.

Counter-terrorism police, who the led the investigation into the poisoning of Sergei and Yulia Skripal, said they were assisting local police in the investigation which has been declared a “major incident” by the emergency services. Scientists at Britain’s defence laboratory at Porton Down are carrying out tests to try and establish if there is any connection between the two incidents, British media reported.

The couple, a man and a woman in their 40s, were discovered unconscious at a house in a quiet, newly-built area in Amesbury, a village near the prehistoric monument of Stonehenge. Amesbury is about 12 kilometers (eight miles) from Salisbury, where the Skripals were found slumped on a bench in March in an incident that sparked a bitter diplomatic crisis with Russia.

The two patients “are both currently receiving treatment for suspected exposure to an unknown substance at Salisbury District Hospital,” a police statement said. “They are both in a critical condition.” The hospital is the same one where the Skripals were treated.