<br /> <p>In the wake of a deadly explosion on the St. Petersburg Metro on April 3 that killed at least nine people</a>, numerous Russian metro riders gathered outside the Sennaya Square Metro.</p><p>The blast occurred on a train near the Sennaya Square Station, and forced the closure of the city’s metro and increased security</a> at Pulkovo International Airport.</p><p>The explosion happened as Russian President Vladimir Putin attended a conference in the city.</p><br />
