Bursa police rounded up 7 teachers after a raid against a central bookstore in the city on Monday.
Detainees also included an accountant and two bookstore personnel.
According to state-run Anadolu news agency, 10 suspects were taken into custody as part of an investigation into the Gülen movement, which the government accuses of masterminding the July 15 coup attempt.
Police carried out the operation on the intelligence of a scheduled meeting among Gulen members, according to Anadolu. The suspects are accused of having used ByLock, a smartphone app that Turkish authorities claim to be the top communication tool among Gulen followers.
The movement denies involvement in the coup bid.