The ongoing ethnic clashes once again point to the complicated confluence of ethnic politics and religious extremism in Karachi. (See a video report in Urdu here)
For some useful insights, see Dawn April 30, 2009: The Karachi Question: Ethnicity or Extremism? by Huma Yusuf.
On the specter of Talibanization in Karachi and its possible connection to ethnic politics, see political analyst, Ayesha Siddiqa's column published on August 15, 2008: State within State. My comments on this piece are here.
The MQM claims that the conflict was instigated by land grabbers, drugs mafia, and Taliban inspired elements in certain neighborhoods (see a video report in Urdu here). It has also demanded that the IJ Sindh and CCPO Karachi should be removed. In their assessment, the IJ Sindh and CCPO Karachi apparently put some blame on the MQM.