|PIC1|The attackers bound their victims before slitting their throats in the publishing house in Malatya, a city in central Turkey and a nationalist stronghold.
Four people are believed to have been detained for questioning regarding the killings, and one other suspect that fell from the building was taken to the hospital with head trauma.
It has emerged that one of those murdered was of German nationality, German Ambassador to Turkey Eckart Cuntz said.
Images appeared on television stations showing police leading several young men out of the building where the killings took place.
Political tensions are rising in the secular but largely Sunni Muslim country over the past year, with Armenian-Turkish editor Hrant Dink being shot dead by an ultranationalist youth earlier this year.
Late last year the head of the Roman Catholic Church, Pope Benedict XVI, paid a short visit to Turkey to ease relations, but during the visit a number of protests broke out in Istanbul. There have been reports of an increase in violence against Christian clergy since the visit.
Christian missionaries are routinely accused by Turkish nationalists of attempting to undermine Turkey's political and religious order.
The EU has clamped down on hostilities towards Christian missionaries in Turkey, however, telling the country that the Christian minority must be given more religious freedom in order to reach the level of religious freedom acceptable for entry to the EU.
Carlos Madrigal, an evangelical pastor in Turkey, told Reuters: "We would like a government campaign to get rid of the myths, such as that missionaries are trying to divide the country, these are the things which feed such acts.
"In some ways the situation has improved because we have got legal rights ... but there are parts of society which have become radicalised."