General view of the front of a house where a suspect was detained by police during a raid in the Kreuzberg district of Berlin, Germany February 4, 2016.

German police on Sunday searched the homes of two men suspected of being part of an extremist organization, prosecutors said.

Federal prosecutors said that the raid took place near the western city of Mainz. The two men are “suspected of taking part in the Syrian civil war as members of a foreign terrorist organization,” prosecutors’ office spokesman Michael Neuhaus said in an email.

He declined to provide further details, including whether the men had been arrested, citing the ongoing investigation.

News website Spiegel Online reported that it had tracked down one of the men – a 32-year-old suspected former commander in the Islamic State of Iraq and Syria (ISIS) group – before the raid in Sankt Johann, a town about 20 kilometers (12 miles) south of Mainz.

The man had allegedly fought with ISIS in the eastern Syrian city of Deir ez-Zor before leaving via Turkey and claiming asylum in Germany.

Federal prosecutors declined to confirm those details.

On Thursday, German police conducted raids in Berlin and western Germany against four Algerian men suspected of having ties to ISIS and plotting an attack in Berlin. One of the men had registered in Germany as a Syrian refugee, police said.

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