The Counter-Terrorism Department arrested on Friday two suspected target killers belonging to the London chapter of Muttahida Qaumi Movement, officials said.
The suspects were arrested during a raid near the Nagan Chowrangi area, a senior CTD official said at a press conference. They were identified as Mohammad Jan and Asadullah Khan.
The CTD official said the arrested hitmen had confessed to murdering six people and dumping their bodies.
He said the suspects opened fire on political rallies and set several vehicles ablaze in Karachi on May 12, 2007.
They were said to be close companions of former MQM office-bearer Hammad Siddiqui.