An explosion at a side entrance to the U.S. embassy in the Turkish capital Ankara killed at least one person and wounded several others on Friday and Turkish state media cited witnesses as saying was the attack was carried out by a suicide bomber.
A Reuters witness saw one wounded person being lifted into an ambulance as police cordoned off the area following the explosion, which sent smoke and debris flying into the street.
Some reports said two security officials were killed in the blast. Police in Ankara had no immediate comment.
Television footage showed a door blown out and masonry from the wall around it scattered in front of the side entrance, although there did not appear to be any more significant structural damage to the building.
"It was a huge explosion. I was sitting in my shop when it happened. I saw what looked like a body part on the ground," said travel agent Kamiyar Barnos whose shop window was shattered around 100 metres away from the blast.
Islamist radicals, far-left groups, far-right groups and Kurdish separatist militants have all carried out attacks in Turkey in the past.
The main domestic security threat comes from the separatist Kurdistan Workers Party (PKK), deemed a terrorist group by the United States, European Union and Turkey, but the PKK has focused its campaign largely on domestic targets.
Turkey has led calls for international intervention in neighbouring Syria and is hosting hundreds of NATO soldiers from the United States, Germany and the Netherlands who are operating a Patriot missile defence system along its border with Syria, hundreds of kilometres away from the capital.
The U.S. Patriots were expected to go active in the coming days.
The most serious attacks of this kind in Turkey occurred in November 2003, when car bombs shattered two synagogues, killing 30 people and wounding 146. Authorities said the attack bore the hallmarks of al Qaeda.
Part of the HSBC Bank headquarters was destroyed and the British consulate was damaged in two more explosions that killed a further 32 people a week later.