MOSCOW (AP) — Russia's Federal Security Service says it has arrested a suspected organizer of the suicide bombing in the St. Petersburg subway that killed 14 passengers.

The service, the FSB, said Monday the suspect was arrested in Odintsovo, a city just outside Moscow. It said the suspect was armed with a pistol and was of Central Asian origin, but did not elaborate.

The bomber in the April 3 blast was from Kyrgyzstan. The impoverished, predominantly Muslim countries in Central Asia are seen as fertile ground for Islamic extremists. Thousands of their citizens are believed to have joined the Islamic State group.

The FSB said the man arrested Monday was believed to have helped prepare the suicide bomber. At least eight others have been arrested in connection with the bombing.