ROME (AP) — Police in Greece have arrested three Pakistani nationals for holding hostage 16 migrants without authorization to be in the country and demanding money for their release.

Police said Sunday that the three were “members of a human traffickers’ network” and that 13 of the migrants they were holding were fellow Pakistanis, three of them minors.

Two of the held at a farmhouse outside the northern city of Thessaloniki were from India and one was from Nepal.

Police say all 16 crossed into Greece from Turkey about two weeks ago and that the people holding them demanded 2,500 euros ($2,654) from each to release them.

One of the Pakistani migrants escaped the farmhouse and notified police, who launched an operation Saturday night.