At least four staffers from Osmangazi University in central Turkey were shot dead by a research assistant, security officials said on Thursday.
Police had detained the shooter, CNN Turk said.
The Dogan news agency said police have apprehended the gunman.
In a statement, the university's rector said those killed were the deputy dean of the education faculty, Mikail Yalcin; the faculty's secretary, Fatih Ozmutlu; lecturer Serdar Caglak; and assistant lecturer Yasir Armagan.
Reports suggest the assailant - named by state media as Volkan B - surrendered after initially trying to escape.
More than 50,000 people have been jailed on suspicions of links to Gulen.
Turkey has been under a state of emergency since the coup attempt.
There was no confirmation from authorities on those claims.
Ayse Aypay, a professor at the university, told Turkish media that some members of staff had "repeatedly filed complaints" about the gunman.
Turkish Governor Ozdemir Cakacak said the Chief Public Prosecutor's Office in Eskisehir province had appointed three prosecutors to probe the incident.