Number of detainees increased to 20 after Sunday night's armed attack against popular Turkish singer Ibrahim Tatlises, Anadolu Agency reported.
Police raided several places in Istanbul and detained 20 people. The automobile and the Kalashnikov rifle used by the assailants during the attack were also found.
59-year-old Tatlises was shot in the head when gunmen opened fire on him as he left a TV studio late on Sunday. His spokeswoman, Buket Cakici, was also injured in the attack.
The singer, also a businessman with interests in tourism and restaurants, had been performing in his music show before the attack.