Istanbul, Turkey ? An outspoken journalist who repeatedly clashed with Turkish authorities here over recognition of the early 20th century slaughter of Armenians was shot to death in broad daylight Friday on a busy downtown street.

Hrant Dink, who as editor of a Turkish-Armenian newspaper was the leading voice for his ethnic community, died a week after he wrote about threats from unknown forces who he said regarded him “an enemy of the Turks.”

Hundreds marched Friday evening from Istanbul’s central Taksim Square to the offices of Dink’s Agos weekly newspaper, near the spot on a sidewalk where he was shot in the head. They held candles and posters with his picture; a somber silence was interrupted periodically with applause and chants for “the brotherhood of peoples.”

Istanbul governor Muammer Guler said late Friday that three people had been detained in connection with the shooting but no additional details were released. The slaying probably will further darken Turkey’s reputation for repressing critics of the government or of the country’s tight control on how its turbulent past is portrayed.

Dink, 52, was part of a group of writers and thinkers, including Nobel literature laureate Orhan Pamuk and novelist Elif Safak, who have been tried on charges of insulting their country’s “Turkishness” under a controversial and ambiguous law promoted by hard-line nationalists.

While most were cleared, Dink was convicted for writing articles that criticized the law and explored questions of Turkish and Armenian identity. He was sentenced to a six-month term, which was suspended.

Last year, an Istanbul court opened a new case against him after he told a foreign news agency that the slaughter of hundreds of thousands of Armenians by Ottoman Turks before and during World War I was a genocide.

An unidentified relative of journalist Hrant Dink reacts to Dink's death as he is helped by Turkish policemen Friday in Istanbul, Turkey. Dink, one of the most prominent voices of Turkey's shrinking Armenian community, was killed by a gunman at the entrance to his newspaper's offices. Dink, a 53-year-old Turkish citizen of Armenian descent, had gone on trial numerous times for speaking out about the mass killings of Armenians by Turks at the beginning of the 20th century. He had received threats from nationalists, who viewed him as a traitor.

Owning up to genocide has been for Turkey an especially fraught matter. Turkey maintains that the deaths and expulsions that Armenians say claimed 1.5 million victims at the end of the Ottoman Empire were part of a civil conflict in which both Christian Armenians and Muslim Turks were killed.

On Friday, however, Turkish Prime Minister Recep Tayyip Erdogan was among the first to condemn Dink’s “traitorous” and “disgraceful” murder.

“Bullets have been fired at free thought and our democratic life,” Erdogan said at a news conference. He urged calm.

European governments, officials in Washington, D.C., and intellectuals across the globe also deplored the murder.

U.S. State Department spokesman Tom Casey said, “We certainly are concerned any time someone who has been very outspoken in their views is made to pay a price simply for their ability to speak their mind.”

Turkish television Friday showed copies of letters containing death threats that Dink said he had received in the past year. He said his pleas for official protection went unanswered.