At least 28 people were killed and dozens of others were hurt Wednesday when a large explosion rocked Ankara, Turkey's deputy prime minister said.
The blast in the Turkish capital happened during rush hour, about 330 yards from military headquarters, according to the Associated Press. Deputy Prime Minister Numan Kurtulmus said the "well-planned" attack was caused by a car bomb and injured 61 people.
The explosion targeted military vehicles that were carrying armed forces personnel, Kurtulmus added. No group took immediate responsibility.
Photos and video on social media showed large plumes of smoke and a burning building. NTV, a Turkish news channel, said several cars caught fire.
The U.S. State Department said it was working to determine whether any Americans were killed or injured and urged U.S. citizens to avoid the area.
The U.S. ambassador to Turkey, John Bass, called the explosion a "terror attack" on Twitter and tweeted that he was "deeply saddened, shocked."