A sustained series of explosions rocked Baghdad, early Wednesday, lasting several hours. It sounded like a massive, sustained fire fight, somewhere southwest of Baghdad -- waking residents in the middle of the night.

An American military spokesman would give few details of what he called an ongoing operation. He said it was related to "Operation Iron Justice," which is aimed at cracking down on insurgents and criminal activity in Baghdad. He the overnight battle involved explosives and aerial activity.

Iron Justice has been underway for nearly a week. But, the capital has not had a fire fight like this in months.

No blasts could be seen from the roof of a hotel in central Baghdad, but scores of explosions were clearly audible, as was the roar of what sounded like machine-gun fire, coming from the south and west of the city.

A private security consultant says it sounded like it could have been the rockets and machine-guns mounted on American Apache attack helicopters.