ISTANBUL — A man approached a visitor’s gate at the US 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 US 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. Erdogan said DNA testing was underway and would be announced Saturday.
A White House official said that it was too early to determine who was behind the attack and that the United States would conduct its own investigation.
The bombing immediately called to mind the attack on a US diplomatic facility in Benghazi, Libya, more than four months ago that was carried out by Islamist extremists and killed the US ambassador there and three others. That episode touched off a politically charged debate in Washington about the protection of diplomats in the volatile Middle East, and it led to the tightening of security and heightened fears about Islamist militant extremism.
On Friday, after the Ankara attack, the State Department immediately warned American citizens to temporarily avoid US 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 guard yelled, ‘‘Run away, a bomb!’’ according to NTV. The footage then went black.
Ambulances and the police rushed to the scene. A Turkish journalist on her way to have tea with the US 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.
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 Erdogan later identified as the Revolutionary People’s Liberation Party-Front, a Marxist-Leninist organization responsible for attacks on US targets in Turkey in the early 1990s.
Still, the White House spokesman, Jay Carney, said in a briefing in Washington, ‘‘We do not know at this point who is responsible or the motivations behind the attack.’’ The findings by the Turks were treated with suspicion by some terrorism specialists.
The group 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 in September.
Ali Nihat Ozcan, a senior fellow at 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 support for the insurgency in Syria.
“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,’’ Ozcan said.
There also was some speculation that the bombing may have been meant to protest the recent deployment of US-made Patriot antimissile systems here, which were requested by Turkey after Syria lobbed shells across their shared border. But Defense Secretary Leon E. Panetta, in an interview with CNN, said there was no evidence of such a connection.