LONDON (AP) — British police say there is no evidence that the nerve agent Novichok was involved in case of two people who became ill in a Salisbury restaurant, but the premises remain closed off.

Wiltshire Police said Monday that the two people who fell ill at an Italian restaurant had been clinically assessed and there was no evidence of Novichok.

Authorities responded with extreme caution after two diners became ill, in light of the March poisoning of ex-Russian spy Sergei Skripal and his daughter and the subsequent poisoning of two others who came into contact with Novichok.

Police have not released the names of the two diners, a man in his 40s and a woman in her 30s. Both remain hospitalized.

British officials blame the Russian government for the Novichok attack.