THESSALONIKI, Greece (AP) — Greek police detained 214 Syrian refugees after they crossed a river that forms a natural border with Turkey, authorities said Wednesday.

The announcement marked the second recent mass crossing of the Evros River — 107 refugees were detained in the same border area last week.

A police official told The Associated Press that refugees and other migrants were taking advantage of current low river levels near the border town of Orestiada. The official wasn’t authorized to speak to the news media and asked not to be identified.

Migrants are seeking alternative routes to the European Union after a crackdown on crossings to the Greek islands started in March, as part of an agreement between the EU and Turkey to stop the flow of migrants and refugees to Europe.

More than a million migrants and refugees crossed through Greece and on to other EU countries since the start of 2016, while over 60,000 have been stranded in the country since the EU-Turkey deal took effect and the Balkan transit route north was closed.

According to Greek police estimates, about 200 people try to cross the border into Macedonia every day, seeking breaks in the razor wire frontier fence as it runs along rugged terrain.

Police in the Greek border area recently stepped patrols and are checking all the trains passing from Greece to Macedonia.

In their attempts to cross borders, some migrants are paying people traffickers. But others, like 35-year-old Afghan refugee Kazem Gasig, are trying to find their own way through the mountains.

“I set off last night from Athens to Thessaloniki, then from here I plan to go to (the border town of) Idomeni, then I will cross the Macedonia border on foot,” he told the AP.

“I have decided to go forward with the help of Google Maps, as far as I can. If I reach a point where I see I can’t move on by my own, I’ll have to go with human traffickers and use a guide.”

(Mstislav Chernov in Idomeni, Greece, contributed.)