A bomb that exploded in Moscow on Wednesday outside a training school for the Federal Security Service (FSB) was detonated using a cell phone, a police source said on Thursday.
The explosion ripped through a bus stop at 4.30 pm Moscow Time (13:30 GMT) in southern Moscow, injuring no one.
"While searching the site of the blast, specialists found parts of a cell phone, which was probably used to detonate the bomb," the source said.
A law enforcement source told RIA Novosti earlier on Thursday that the bomb was detonated using a timer device.
A source close to the investigation told RIA Novosti that investigators were studying the possible involvement of terrorist groups in the explosion.
According to preliminary information, the blast on Michurinsky Prospekt near the Universitet metro station was equivalent to 200-400 grams of TNT.
MOSCOW, March 10 (RIA Novosti)