A bomb exploded Wednesday night at the Istanbul offices of Adimlar, a magazine that supports the Islamic State group. The blast killed a writer and injured three other people, including the editor-in-chief.

The bomb was left at the main entrance of the magazine's office in the Kagithane district and detonated when the door opened, Turkish police told the Associated Press.

Adimlar is a radical magazine that prints anti-Western content and is published by supporters of the Great Eastern Islamic Radiers’ Front (IBDA-C), a militant group that supports Islamic rule in Turkey, the Daily Sabah, a Turkish newspaper, reported.

Editor-in-Chief Ali Osman Zor, who was wounded in the blast, has defended the brutal methods of the Islamic State group, which is also known as ISIS or ISIL. Last year, Zor told CNN that ISIS attacks were a natural response to so-called Western imperialism in the Middle East and the persecution of Sunni Muslims in Iraq by Kurds and Shi’ite Muslims.

Zor’s brother, 45-year-old Unsal Zor, was the writer killed in the blast, which destroyed the building’s exterior wall and damaged neighboring structures. Those injured were taken to nearby hospitals, the Daily Sabah reported.

Turkish police have not yet identified any suspects or disclosed a motive for the attack, and there were no immediate claims of responsibility. But an anonymous staff member of the magazine told CNN on Thursday, “We know this to be the work of CIA and Mossad. We know this is an intelligence operation.” [The CIA and Mossad are the intelligence agencies of the United States and Israel, respectively.]

Earlier this year, terrorists killed 12 people at the Paris office of Charlie Hebdo, a satirical magazine that frequently publishes controversial cartoons on Islam and the Prophet Muhammad.