The private NTV news channel said there were at least three dead and 15 people wounded and showed footage of one body lying on the ground covered in newspaper.
But a police spokesman said he was sure no one had been killed in the blast.
Deputy Prime Minister Mehmet Ali Sahin said the cause of the explosion in Ankara's Anafartalar shopping area was not yet clear.
Police cordoned off the area of the explosion and windows of shops in the area were shattered and many ambulances were sent to the area. Police are evacuating the area.
The explosion happened during rush hour, raising the number of the wounded.
Reuters NC GC2242