A St Petersburg underground station closed after a bomb threat on Tuesday has reopened, Russian news agency RIA reported.
Sennaya Ploshchad station was shut earlier after an anonymous call warning of a bomb.
Monday's deadly blast happened on a train as it travelled between Sennaya Ploshchad and Tekhnologichesky Institut underground stations.
The seven people were from Central Asian countries and investigators say they were recruiting for IS.
The bombing of a subway train in Russia has drawn condemnation from world leaders.
A blast has ripped through an underground train in Russia's second-largest city on Monday.