Three women of unknown origin were found dead, presumably murdered, on Wednesday on the Greek side of the river border between Turkey and Greece, police sources said, an area known for illegal migrant crossings.

The bodies, found in a field by a passerby, lay a short distance from each other near a migration route from Turkey over the Evros River frontier to northeastern Greece, though it was not yet known whether the women were migrants.

Police said they suspected foul play. All three had stab wounds, the semi-official Athens News Agency (ANA) reported.

“They were found 50 metes away from the river,” a police official told Reuters. Two of the victims were believed to be aged between 15 and 18 and it was possible they were related, ANA said.

The Evros border area straddles an old people smuggling corridor that regained popularity after European Union and Turkish authorities in 2016 sealed off sea routes in the Aegean used by hundreds of thousands of migrants in 2015.

In the first half of 2018, more than 10,000 migrants and refugees arrived in Greece from Turkey by crossing the Evros, a nongovernmental aid agency said in August.