The Syrian state news agency said the cars packed with explosives detonated early in the morning in the eastern Jaramana district, which is mostly loyal to president Bashar al Assad. It said at least 34 people died.
A series of blasts have struck regime targets since last December, increasing fears of a rising Islamic militant element among the forces seeking to topple the Assad government.
The bombs went off in a car park between two commercial buildings. They were detonated within five minutes of one another as groups of labourers and employees were arriving for work.
The blasts shattered windows in nearby buildings, littering the street with glass and debris. Human remains were scattered on the pavement amid pools of blood. After the first explosion, people rushed to the site to help the injured and then the second bomb went off, said Ismail Zlaiaa, 54, who lives nearby.
The Britain-based Syrian Observatory for Human Rights said 29 people were killed. The state SANA news agency put the toll at 34.