Police in Istanbul arrested seven people for their suspected links to the PKK terrorist organization on Friday.

The law enforces obtained an intelligence suggesting a group of PKK members had entered Turkey illegally and were plotting to conduct terrorist acts in Istanbul.

An investigation was launched and seven suspects were arrested in different raids. The police also confiscated organizational and digital documents.

In its more than 30-year terror campaign against Turkey, the PKK — listed as a terrorist organization by Turkey, the U.S. and the European Union — has been responsible for the deaths of nearly 40,000 people, including

Read more: 7 PKK-linked terror suspects arrested in Istanbul