ISTANBUL, Turkey (USA TODAY) -- A suicide bomber attacked the U.S. Embassy in the Turkish capital of Ankara, killing one Turkish security guard along with the bomber, Ankara Govenor Aladdin Yuksel told Turkish news media.
The explosion went off at the entrance used by the embassy personnel and their visitors, after a lone suicide bomber passed through the x-ray machine, Turkish news media reported.
News reports said that there is no damage inside the embassy and that all personnel have been moved to safe rooms inside the building. Turkish television footage showed a door blown out and pieces of the wall around it scattered in front of the entrance.
Turkish daily newspaper Sabah posted a shaky video that was taken at the scene shortly before the area was closed off, showing Turkish police officials angrily asking that filming be stopped. Police said they suspected a second bomb which is why they blocked off the area.
There has been no claim of responsibility.
According to Turkish media, the suicide bomber was a middle-aged man of non-identified nationality. Vatan newspaper, whose reporter witnessed the explosion, said it was severe and damaged the surrounding buildings and cars nearby.
U.S. Ambassador in Ankara, Francis Ricciardone, said Turkish and U.S. officials will work together to determine who carried out the attack. Turkey's foreign minister Ahmet Davutoglu expressed his sorrow.
"I am offering my condolences to the relatives of those who lost their lives, and my best wishes to everyone at the American embassy and the foreign ministry," he said. "Our whole security apparatus is working full force on finding the ones responsible for this attack and we are hoping to clarify the matter shortly."
Turkey, a member of NATO, has come under attack from a number of groups operating on its territory including Kurdish separatists, leftists and Islamist militants, with the last major attack in Ankara in 2007 blamed on a solo suicide bomber: It killed nine people and injured 120.
Aaron Stein, an analyst at the Center for Economics and Foreign Policy Studies at King's College in London, said: "This could be a lone wolf, it could be linked to groups in Syria, it could be al-Qaeda. My initial reaction is that this was similar to the 2003 attacks in Istanbul (against British targets which killed 58), which were linked to al-Qaeda."
At this point it's difficult to even speculate who might have been behind the attack, said Marina Ottaway, a Middle East analyst at the Woodrow Wilson International Center for Scholars in Washington.
There are multiple terrorist groups operating in the region. The PKK, the Kurdistan Workers' Party, has launched the most violent attacks in Turkey, but it has no incentive to provoke the United States, Ottaway said.
The Kurds have generally good relations with the United States. It was largely the United States that maintained a no-fly zone over northern Iraq to protect the Kurds there from Saddam Hussein's murderous pogroms against them.
Al Nursra Front, al-Qaeda's affiliate in Syria, seems an unlikely suspect because it has used very few suicide attacks and its fighters have been focused on a ground war in Syria, taking military bases and cities, she said. "This would be a distraction," she said.
Hezbollah, the Iranian-backed and Syrian-allied Shiite militia in Lebanon, has launched suicide attacks against the United States in the past and it could be using the recent Israeli airstrike in Syria as a motive, Ottaway said.
Or the attack "could be a minor group trying to calling attention to itself," she said. "Anything would be speculation at this point."