The explosion, which officials said was caused by a bomb possibly carried in a bag or backpack, struck the main railroad station in Volgograd, a city about 550 miles south of Moscow, at 12:45 p.m. It blew out windows in the building’s facade and left a horrific scene of carnage at the station’s main entrance.
The blast, captured on a surveillance video camera from across the central plaza in front of the station, occurred near the metal detectors that have become a common security fixture at most of Russia’s transportation hubs, suggesting that an attack deeper inside the station or aboard a train might have been averted.
Vladimir I. Markin, a spokesman for the Investigative Committee, called the bombing an act of terrorism, though the exact motivation, target and perpetrator were not immediately clear. Within hours of the attack, the authorities blamed a suicide bomber, citing the gruesome discovery of a woman’s severed head, which, they said, could aid in identifying her.
“Most likely, the victims could have been much higher if the so-called protective system had not stopped the suicide bomber from getting through the metal detectors into the waiting room where there were passengers,” Mr. Markin said in a statement on the committee’s website.