MOSCOW, April 2 (RAPSI) – Four Russian nationals were arrested in Gaziantep, southern Turkish province, for allegedly trying to cross into Syria, RIA Novosti reported on Thursday.

Authorities of Gaziantep announced in March that 59 Russian nationals had been arrested since the beginning of the armed conflict in Syria for trying to join the Islamic State (ISIS) terrorist organization.

The rapid expansion of ISIS, which has taken over vast areas in Iraq and Syria, was one of the largest international issues in 2014. The organization, which the CIA has estimated to comprise about 30,000 militants, has declared caliphate in the seized territories.

Since the beginning of the conflict, several thousand civilians have died, hundreds of thousands have fled their homes and several thousand are held hostage by ISIS. Volunteers from over 80 countries have joined ISIS in Syria and Iraq. Many of them cross into these countries from Turkey.