After more people were killed in different parts of the city in targeted killings the MQM called for a day of mourning on Saturday.
As expected the city wore a deserted look due to the mourning day with all shops, petrol pumps, educational institutions, banks shut down as heavy contingents of police and rangers patrolled the city.
The fresh violence erupted late night when armed gunmen opened fire on the busy commuter bridge in Banaras which is considered a stronghold of the ethnic Pushtuns.
In the firing six bikers were injured and four of them later succumbed to their injuries, including a father-son duo.
The deceased were said to belong to the Urdu speaking population which is represented by the Mutthaida-e-Qaumi Movement which is the largest single party in Karachi. Senior police officials said that they had ordered the immediate arrest of the policemen who were posted on duty at the Banaras bridge when the tragic firing incident took place. Ten people were killed in other violent incidents in the city since last night.
The Rangers also carried out raids in different parts of the city also targeting the strongholds of MQM and Awami National Party which represents the Pushtun speaking people.
According to details around 75 people were detained by the Rangers on suspicion of being behind the recent wave of violence and killings in the city. The day of the mourning was the third day this week that a complete strike has been observed in the city bringing to a standstill normal life in Pakistan`s financial hub.
Around 30 people have been killed in the different incidents of violence in Karachi since Monday when a senior activist of the MQM was shot dead in PIB colony along with his brother.
Earlier in the day, the chief justice of Sindh High Court had taken notice of the situation in the city and had asked DG Rangers and IG Police to file detailed reports.
President Asif Zardari also reached the city last night and was expected to chair a high level meeting on Saturday evening to review the law and order situation in Karachi.