What's going on in Baghdad/Iraq?

There's fighting going on in the city that started after Shia militas stormed the Green Zone and the presidential palace. Combat footage is all over twitter right now, talks of civil war is coming up, neighbors are closing their borders, but honestly I don't really get what's going on. Pro-Iran vs Anti-Iran militias and interests are playing a role from what I've gathered, but that's about it.

Anyone more familiar with Iraq and today's events?