2017 Saint Petersburg Metro bombing
On 3 April 2017, a terrorist attack using an explosive device took place on the Saint Petersburg Metro between Sennaya Ploshchad and Tekhnologichesky Institut stations. Eleven people (including the perpetrator) were initially reported to have died, and five more died later from their injuries, bringing the total to 15.
Source: Wikipedia — 2017 Saint Petersburg Metro bombing (CC BY-SA 4.0)