Turkish authorities detained Eyüpsultan Mayor Mithat Bülent Özmen and 27 other suspects earlier Friday as part of a corruption investigation involving the Istanbul district municipality, prosecutors said.

The Ankara Chief Public Prosecutor’s Office said detention orders were issued for 28 suspects over allegations including membership in a criminal organization, receiving and giving bribes and bid rigging.

All 28 suspects were detained in simultaneous operations carried out by financial crimes police, according to the prosecutor’s office. Authorities also conducted searches and seizures at addresses linked to the suspects and searched the Republican People’s Party (CHP)-run Eyüpsultan Municipality building.

Prosecutors said the investigation was being conducted in coordination with the Ankara Police Department’s Financial Crimes Investigation Branch.

"The investigation continues in a comprehensive and meticulous manner,” the prosecutor’s office said.

Özmen, who serves as mayor of Istanbul’s Eyüpsultan district, was among those taken into custody.

The detentions are part of an ongoing investigation, and no court has ruled on the allegations against the suspects.