State-run Ikhbariya news channel showed blurred images of what looked like a blackened girl's head in a blanket, and scenes of destruction inside what it said was the police station.
State news agency SANA, quoting a Damascus police source, said there was an explosion in the police station.
A witness in the area of the blast told Reuters a young girl entered the police station and, after asking to go to the toilet, blew herself up.
The Syrian Observatory for Human Rights said there had been an explosion in the Midan area and there were reports of casualties.
Sky News also reported that three people have been killed in the bomb attack and four others have been injured.