Both the injured - a man and a woman --have been admitted to a hospital, City Police Commissioner M N Reddi told reporters.
One was serious and the other out of danger, he said, describing the blast as a low-intensity explosion.
The blast occurred around 8.30 pm on the bustling Church Street in the heart of the city and it was caused by an IED, Reddi said.
Police have cordoned off the area and mobilised additional forces, he said.