One person was killed and over 30 were injured on Tuesday when a bomb planted on a motorcycle went off near the headquarters of the Mutthaida-e-Qaumi Movement and a park where the MQM had just finished holding a massive rally.
Senior police official, Imran Shaukat confirmed that the bomb was planted on a motorcycle and apparently the target were the buses parked in the vicinity waiting to take the participants of the rally back to their homes.
"We have initial reports off about 20 people being injured while the area is being combed by the bomb disposal squad to ensure they are no more explosions," Shaukat said.
But other reports said that as many as 30 people had been injured, some of them seriously, in the attack.
The blast that occurred at Aisha Manzil caused panic and fear in the city and led to massive traffic jams and bottlenecks with shops and petrol pumps closing down.
Though MQM leaders have been killed in target killings in the past, this is the first time that terrorists have directly targeted the MQM in a bomb attack.
MQM, which is the largest single party in Pakistan's biggest city, has its headquarters close to Aisha Manzil and the Jinnah Park is used regularly for its rallies.
The blast took place just after MQM chief, Altaf Hussain had finished addressing the massive rally.
The leader of the Minhaj ul Quran, Tahir ul Qadri, had also visited the MQM headquarters on Tuesday to formally seek their support and participation in a big rally planned on January 14 to march on Islamabad against a corrupt government and electoral system.
On Monday, the MQM coordination committee had announced its support and participation in the rally.
The outlawed Tehreek-e-Taliban have said they would target MQM leaders and supporters after Altaf Hussain urged the government and people to unite and wage a war against the militants following the attack on child activist Malala Yousufzai.
Television channels reported that the blast which was heard in nearby areas had damaged shops and buses which were waiting to transport people who attended the rally.
Last week, a bomb blast on a passenger bus in the busy Cantt area had left six people dead and around 50 injured.