Explosion shakes Baghdad's Green Zone

At least one explosion was heard inside the heavily fortified Green Zone in central Baghdad today.

The Zone houses the Iraqi government and several foreign embassies.

A plume of smoke could be seen rising from near the helicopter landing field inside the Zone immediately after the blast.

Sirens sounded the alarm.

Security in the zone was boosted earlier this month after reports that suicide bombers were trying to penetrate the area, which is a frequent target for insurgent attacks.