A suicide bomber suspected to be a militant from an outlawed leftwing group blew himself up at the US embassy in Ankara on Friday, killing a Turkish security guard and wounding several other people, officials said.
The bombing at a security roadblock near the entrance to the highly-fortified embassy in an upmarket area of the capital was the latest in a series of attacks on American missions in the Muslim world.
US vice president Joe Biden, on a visit to Germany, said the attack had been "characterised by our embassy as a terrorist attack".
"We lost one of the three guards at the entrance, while the two others survived with injuries," Turkey's interior minister Muammer Guler said, adding that a female journalist was also seriously wounded.
He said the bomber was believed to be a member of an illegal "left wing terrorist organisation", without elaborating. US warns citizens against visiting Turkey
The attack came two weeks after a major nationwide crackdown on the Revolutionary People's Liberation Front (DHKP-C), a Marxist group blamed for several acts of terror in Turkey since the late 1970s, including suicide attacks, but Guler did not confirm.
There was no immediate claim of responsibility for what is the latest of many bloody attacks in Turkey which in the past have been blamed on Kurdish militants, leftist extremists or al Qaeda-linked groups.
Friday's bombing came on the last day of Hillary Clinton's tenure as US secretary of state and a week after Nato declared that a battery of US-made Patriot missiles went operational on Turkey's border with war-torn Syria.
US ambassador Francis Ricciardone vowed to work with Turkey to fight terror, confirming the death of the Turkish security guard and saying: "The compound is secure."
In September, the US ambassador to Libya and three other people were killed when dozens of heavily armed al Qaeda-linked militants overran the US consulate in Benghazi.