ANKARA, Turkey — A car bomb went off near bus stops in the heart of Turkey’s capital on Sunday, killing at least 27 people and wounded around 75 others, officials said. The blast occurred on the city’s main boulevard, Ataturk Bulvari, close to Ankara’s main square, Kizilay, and a park. The private NTV news channel said a car, believed to be laden with explosives, detonated close to a bus.