ISTANBUL -- A man approached a visitor's gate at the American Embassy in the Turkish capital Ankara Friday afternoon and detonated an explosives-packed vest, killing himself and a Turkish security guard, blowing a gaping hole in the wall and raising new fears about the protection of American diplomats serving in this region.
Within hours Turkish authorities blamed the attack on a homegrown Marxist organization, and Friday evening Prime Minister Recep Tayyip Erdogan said the issue had "pretty much been clarified" because the bomber had been identified, by a skin mark on his head, as a former prisoner once incarcerated for domestic terrorism. Mr. Erdogan said DNA testing was under way and would be announced on Saturday.
A White House official said it was too early to determine who was behind the attack, and the United States would conduct its own investigation.
The bombing immediately called to mind the attack on an American diplomatic facility in Benghazi, Libya, more than four months ago that was carried out by Islamist extremists and killed the American ambassador and three others. That episode touched off a politically charged debate in Washington about the protection of diplomats serving in the volatile Middle East, and led to the tightening of security protocols and heightened fears about Islamist militant extremism.
On Friday, after the Ankara attack, the State Department immediately warned American citizens to temporarily avoid American diplomatic offices in Turkey.
Just after lunchtime, according to images captured on a security camera and reported by the Turkish television channel NTV, a man entered a security checkpoint near the consular section and began to panic as the metal detector buzzed. When he reached for his midsection, a Turkish security guard yelled, "Run away, a bomb!" according to NTV. The footage then went black.
Ambulances and police rushed to the scene. A Turkish journalist on her way to have tea with the American ambassador, Francis J. Ricciardone Jr., was critically wounded.
Alaaddin Yuksel, the governor of Ankara, told reporters in televised remarks that the explosion took place at a security entrance to the embassy grounds. He spoke in front of the main embassy building, which appeared undamaged. "We've had hundreds of phone calls, in the first minutes, hundreds of text messages of condolences and support," Mr. Ricciardone told reporters, standing with Mr. Yuksel. "We feel we are among friends. We feel safe. Thank you for sharing our pain and sorrow on this occasion. We will continue to fight terrorism together."
Hours after the attack Interior Minister Muammer Guler said an initial investigation had identified the bomber as having been a member of an outlawed leftist group that Mr. Erdogan later identified as the Revolutionary People's Liberation Party-Front, a Marxist-Leninist organization which was responsible for attacks on American targets in Turkey in the early 1990s.
However, the White House spokesman, Jay Carney, said in a briefing with reporters in Washington, "We do not know at this point who is responsible or the motivations behind the attack." And the Turks' findings were treated with suspicion by some terrorism experts.
"I'm rarely stumped on these things, but I am stumped," said Bruce Hoffman, a terrorism expert at Georgetown University in Washington. He explained that Islamic terrorism would seem far more likely, and the swift manner in which the Turks said they had cracked the case raised eyebrows. "When a terrorist crime is solved within 24 hours it is suspicious," he said.
The State Department warning to American citizens said they should avoid United States diplomatic missions in the country "until further notice." It also advised Americans traveling or residing in Turkey "to be alert to the potential for violence, to avoid those areas where disturbances have occurred, and to avoid demonstrations and large gatherings."
The group that Turkish officials blamed for the attack is on the State Department's list of terrorist organizations and has mainly targeted Turkish officials and generals. It was held responsible for the assassination of a former prime minister in 1980 and a suicide attack on a police station in Istanbul last September. It was also a played a role in the political violence that convulsed Turkey in the late 1970s and prompted a military coup in 1980 to restore order.
Ali Nihat Ozcan, a terrorism expert with the Ankara-based Economic Policy Research Foundation, said the group had in the past received support from Syria and suggested the attack -- if the group's involvement is confirmed -- may have been related to Turkey's policy of supporting the rebels fighting to oust the Syrian government.
"We are talking about a highly marginal but dedicated urban terror group that has a large Arab Alawite membership, and tied to the Syrian intelligence with strong historical links since 1980s," Mr. Ozcan said.
Turkish-American relations are strong and friendly, but Turkey has not been immune to anti-American attacks in recent years. In 2008, three gunman attacked security guards outside the American consulate in Istanbul in a shootout that left the attackers and three police officers dead. In 2003 truck bombs targeted the British consulate, HSBC bank and two synagogues in Istanbul, killing dozens in an attack blamed on Al Qaeda.
Reporting was contributed by Rick Gladstone from New York, Michael R. Gordon from Washington, and Nicholas Kulish from Berlin.
This article originally appeared in The New York Times.