Two security guards were killed and several other people were wounded in a blast outside the US embassy in Ankara on Friday, local television reported.
The force of the blast damaged nearby buildings in the Cankaya neighbourhood where many other state institutions and embassies are also located.
Police have cordoned off the area.
NTV television said two security guards were killed and several people wounded.
US embassy staff were not immediately reachable for comment.
In July 2008, three gunmen and three Turkish policemen were killed in an attack outside the well-fortified US consulate in Istanbul.