Initial reports suggest the political office, set up for election campaigning in the city's NA-250 constituency, was the target of suspected terrorists. Several party activists are among the injured.
"The MQM office is located in a lane close to the Fresco roundaround where a few metres away the food street is located so as soon as the blast took place there was lot of panic and fear and the food street and markets have now closed down as rescue operations continue," a police official said.
This is the fourth bomb attack on a MQM office since last week when three blasts took place in North Nazimabad and Orangi Town areas while in a fourth incident a election office of the Awami National Party was also bombed.
The outlawed Tehreek-e-Taliban have vowed to target these parties in the run up to the elections because of their secular policies.