Who’s who - (copied from another forum:)

Currently, there are either two or three groups who are suppressing the students on the ground that you’ll read about throughout this thread:

1. The Basij
2. Ansar Hizbullah (which I will refer to as Ansar)
3. Lebanese Hizbullah (Unconfirmed but highly probable. Many different independent reports and video point that way. Even in the last hours other independent twitter feeds have declared witnessing thugs beating on people while shouting in Arabic; I will refer to them as Hizbullah)

- The Basij are your regular paramilitary organization. They are the armed hand of the clerics. The Basij are a legal group, officially a student union, and are legally under direct orders of the Revolutionary Guard. Their main raison d’tre is to quell dissent. They are the ones who go and crack skulls, force people to participate in pro-regime demonstrations, and generally try to stop any demonstrations from even starting. They are located throughout the country, in every mosque, every university, every social club you can think of. They function in a way very similar to the brownshirts.

They were the ones who first started the crackdown after the election, but it wasn’t enough. While they are violent and repressive, they are still Persian and attacking fellow citizens. A beating is one thing, mass killings another.

- Another group was working with them, whose members are even more extreme, is Ansar. There is a lot of cross-membership between the Basij and Ansar, though not all are members of the other group and vice-versa. The vast majority of Ansar are Persians (either Basij or ex-military), though a lot of Arab recruits come from Lebanon and train with them under supervision of the Revolutionary Guard. They are not functioning under a legal umbrella, they are considered a vigilante group, but they pledge loyalty directly to the Supreme Leader and most people believe that they are under his control. They are currently helping the Basij to control the riots, but due to the fact that they are Persians and in lower numbers than the Basij, they are not that active.

- (the following paragraph includes some speculation based on reports from ground zero) Hizbullah flew in a lot of their members in Iran, most likely a good deal even before the elections in case there were trouble. They are the ones who speak Arabs and are unleashing the biggest level of violence on the Persians so far. Another wave arrived recently and there is chatter that yet another wave of Hizbullah reinforcements are coming in from Lebanon as we speak. According to Iranians on the ground, they are the ones riding motorcycles, beating men women and children indiscriminately and firing live ammunitions at students.

The Lebanese Hizbullah is a direct offshoot (and under direct control) of the Iranian Hizbullah (itself under direct control of the Supreme Leader) and cooperates closely with Ansar though Ansar occupies itself only with Iran’s domestic policies, while Hizbullah occupies itself only with Iran’s foreign policy unless there is a crisis like right now. However, Hizbullah has been called to stop violent riots in Iran in the past.

What will happen

Unless the army decides to intervene in the favor of the Council and to stop the early beginnings of the new Revolution, Ansar & Hizbullah members will be the ones doing the brunt of the killing and repression with Basij as a support while also protecting government buildings and try to do crowd control. The police seems to have for the most part disbanded in centers like Tehran according to all reports, including international media.