A bomb blast on a subway train in St. Petersburg, Russia, killed at least 10 people and wounded some 39 others Monday, Russian officials said, in what President Vladimir Putin called a possible act of terror. One of the blasts came from a device that appeared to be filled with shrapnel, Sky News reported. Putin said investigators were looking into all possible causes. An unexploded device turned up at a different subway station as crews worked to deactivate it, anti-terror officials said.