Massive explosions rock Baghdad!

"Over the past 90 minutes or so, massive explosions could be heard in Baghdad and actually I'm hearing more of them while I'm typing.
When the first few bangs happened I thought they were just the usual dose of mortars for the night but more and more explosion kept happening!

I went up to the roof to see if anything could be seen from there and I was able to see several flashes coming from the south, south-west side of the city.
Using the simple method of measuring the lag between seeing the flash and hearing the sound I figured out the explosions are taking place somewhere in the area between Karrada and Dora, yet the explosions are very loud that they can be heard in the northern parts of Baghdad!
I'm searching the news for a clue about what's going on but I found nothing so far.

Update (12:35 am):

First news report on the situation is just in.

Reuters says the explosions were caused by a fire that broke out at "an ammunition dump at a U.S. base in southern Baghdad" apparently in the Dora district of Baghdad."
ITM