Russian authorities discover and deactivate an explosive device in a Saint Petersburg flat, during ongoing raids occurring in response to the bombing.
A seventeen-year-old local student, who studied at a nearby polytechnic school, detonates an explosive device inside a Federal Security Service building in Arkhangelsk, Russia, killing himself and wounding three FSB officers. The agency is Russia's primary state security agency and a successor to the KGB.
Ukraine's Joint Forces Operation says Russian-led militants have mounted 43 attacks on Ukrainian troops in Donbas in the past 24 hours, using artillery systems and 120mm and 82mm mortars 10 times, with no casualties among the Ukrainian servicemen. According to intelligence data, two militants are killed and three others wounded.
The United Nations Security Council meets amid concerns of military strikes in Syria by the United States and its allies following a suspected chemical weapons attack in Syria last weekend, with the United States ambassador to the UN, Nikki Haley, accusing Russia of lies and covering for the government of Syrian President Bashar al-Assad, which she said had used chemical weapons at least 50 times in the past seven years of warfare, and the Russian ambassador to the UN, Vassily Nebenzia, blaming the United States, France and the UK for escalating tensions.
An attack on a Saint Petersburg Metro train at Sennaya Ploshchad station kills at least 11 people and injures more than 50 others. Authorities disarm another bomb, found at nearby Vosstaniya Square station.
Russia's Federal Security Service (FSB) says it has thwarted two armed Ukrainian incursions into Crimea with at least two killed, including one FSB officer, following a "massive fire fight" with "sabotage-terrorist" groups. Ukraine denies the Russian claims.
At least thirty pro-Russian separatists have died in fighting over control of Donetsk International Airport; the Ukrainian government claims to have total control of the airport following the clashes with the separatists.