Russian police have arrested a 26-year-old woman in connection with an explosion which took place at a cafe in St Petersburg.
A well-known military blogger, Vladlen Tatarsky, was killed in the explosion, and injured at least thirty two others.
The woman, named Darya Trepova has previously been detained for taking part in protests against the war in Ukraine.
BBC World correspondent Olga Ivshina spoke to Guyon Espiner.
