SALISBURY, England — British media reported Monday that a former Russian spy was in critical condition after coming into contact with an “unknown substance,” a case that immediately drew parallels to the poisoning of former Russian agent Alexander Litvinenko.

Authorities did not identify the man, saying only that he and a woman were found unconscious Sunday on a bench in a shopping mall in Salisbury, about 90 miles west of London.

British media identified him as Sergei Skripal, 66, who was convicted in Russia on charges of spying for Britain and sentenced in 2006 to 13 years in prison. Skripal was freed in 2010 as part of a U.S.-Russian spy swap.

Wiltshire Police, which is responsible for the Salisbury area, only identified the man and woman by their approximate ages and said they appeared to know one another and “did not have any visible injuries.”

“They are currently being treated for suspected exposure to an unknown substance. Both are currently in a critical condition in intensive care,” police said in a statement.

The discovery of the unconscious pair led to a dramatic decontamination effort. Crews in billowing yellow moon suits worked into the night spraying down the street, and the Salisbury hospital’s emergency room was closed.

The BBC, which first identified Skripal as one of the victims, quoted eyewitness Freya Church as saying it looked like the two people had taken “something quite strong.”

“On the bench there was a couple, an older guy and a younger girl. She was sort of leaned in on him. It looked like she had passed out, maybe,” Church said.

Public Health England said in a statement that it had only limited information about the patients, but there “doesn’t appear to be any further immediate risk to public health.”

Skripal served with Russia’s military intelligence, often known by its Russian-language acronym GRU, and retired in 1999. He then worked at the Foreign Ministry until 2003 and later became involved in business.

After his 2004 arrest in Moscow, he confessed to having been recruited by British intelligence in 1995 and said he provided information about GRU agents in Europe, receiving over $100,000 in return.