Shots were fired from a moving car at a security booth outside the U.S. Embassy in Turkey early Monday.
Nobody was injured in the "security incident," which happened at about 5 a.m. local time (10 p.m. Sunday ET) in Ankara.
The U.S. mission is closed this week as Turkey celebrates the Muslim holiday of Eid al-Adha.
The shots were fired from a white vehicle that drove off, a government source told NBC News.
Local media reported that four to five rounds were fired at the security booth and that one bullet hit a window.
Ties between Ankara and Washington have been strained over the case of an imprisoned American pastor, leading the U.S. to impose sanctions and tariffs that sent the Turkish lira tumbling. Turkey retaliated by imposing extra tariffs on U.S. imports of products including rice, vehicles, alcohol, coal and cosmetics.
"We can confirm a security incident took place at the U.S. Embassy early this morning," embassy spokesman David Gainer said in a statement. "We have no reports of any injuries and we are investigating the details. We thank the Turkish National Police for their rapid response."