Investigators say they have not ruled out terrorism as the cause of a blast outside a training center for the Federal Security Service in Moscow on Wednesday.
The bomb tore through a bus stop at 4.30 pm Moscow Time (13.30 GMT) in the south of the city on Wednesday, injuring no one.
"The possible involvement of illegal armed groups in the explosion is being assessed," a source close to the investigation told RIA Novosti.
According to preliminary information, the blast on Michurinsky Prospekt near the Universitet metro station was equivalent to 200-400 grams of TNT and was detonated by a timer device.
MOSCOW, March 10 (RIA Novosti)