BAGHDAD -- Two Katyusha rockets were fired early Sunday on the heavily fortified Green Zone that houses the US embassy in central Baghdad, the Iraqi News Agency (INA) reported.

One of the rockets was destroyed in the air by the C-RAM defense system, which protects the US embassy site, and the other landed near the grand celebrations square in the zone, damaging two civilian cars, the agency said.

According to INA, there were no immediate reports about casualties and that the security forces launched an investigation into the incident.

The Green Zone, which houses some main Iraqi government offices and the U.S. embassy, has frequently been targeted by insurgent mortar and rocket attacks.