MOSCOW — Russia’s Federal Security Service said Monday that it has arrested a suspected organizer of the suicide bombing in the St. Petersburg subway that killed 14 passengers.

The service, the FSB, said 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.

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.

The eight were members of extremist cells, Russia’s intelligence chief said last week.

Akbardzhon Dzhalilov, a 22-year old Kyrgyz-born Russian national, has been identified as the bomber.

Russian authorities have not outlined his possible links to extremist groups but an unidentified law enforcement official told the Tass news agency that investigators were checking information that he may have trained with the Islamic State in Syria.

A Turkish security official has said the suicide bomber was deported from Turkey in 2016.

The official said Dzhalilov had entered Turkey in November 2015 on a tourist visa and was deported to Russia in December 2016 for violating Turkey’s visa laws. He was fined and barred from reentering Turkey for 120 days, the official said.

The official spoke on condition of anonymity in line with government regulations that bar civil servants from speaking to journalists without authorization.

Associated PreSS