The Russian opposition newspaper "Novaya Gazeta" announced Monday that an unknown chemical was dumped at the entrance to its editorial board in Moscow, noting that the newspaper is one of the symbols of the independent press in Russia.

The newspaper’s editor-in-chief, Dmitry Muratov, said, “The building that houses our editorial staff was subjected to a chemical attack this morning. We cannot move between floors nor go out into the street,” adding that the security forces are currently analyzing this material.

This is a developing story.