Security was tightened here on Tuesday, a day after a bomb ripped through a subway station next to the office of Belaruss authoritarian president, killing 12 people, wounding more than 150 and worsening an already tense political situation. Security officers checked passengers at the entrance to the Nemiga subway station in Minsk on Tuesday. A security officcer checked documents near the entrance to the Oktyabrskaya subway station in Minsk on Tuesday. No one immediately claimed responsibility for the explosion in Minsk, the Belarus capital. The police detained several suspects on Tuesday, news agencies reported, but were still searching for the perpetrator. Witnesses described being hit by a wave of shrapnel that they said was contained in the bomb, and paramedics said several victims limbs were torn off by the force of the blast.