KARACHI: A complete shutdown was observed in Karachi and other cities of Sindh on Sunday (today) following a call to observe a 'day of mourning' by the Muttahida Qaumi Movement (MQM) over twin bomb blasts outside their election office in Azizabad on Saturday which killed three people and injured 40 others, DawnNews reported.

A bomb planted near a park where the MQM had set up its election office for its unit in Karachi's Azizabad (Federal B. Area Block 8) went off around 9pm on Saturday.

The blast caused panic and fear in the densely populated and highly guarded neighbourhood as a number of MQM activists, volunteers, personnel of law enforcement agencies and media crew rushed to the place.

About 20 minutes later, another explosion took place at almost the same place which was crowded by the party’s activists, volunteers and security personnel. Police said apparently the MQM election office was the target.

“Both bombs were detonated either by remote control or a timer device,” Karachi Central SSP Amir Farooqi said.“The first attack appears to have been a trap to draw people to the place before the second explosion. Tight security and surveillance prevented any major damage.”

Meanwhile, the Pakistani Taliban have claimed responsibility of the attack. Speaking to Dawn.com via telephone from an undisclosed location, Tehrik-i-Taliban Pakistan (TTP) spokesman Ehsanullah Ehsan said the target was MQM and both bombings were carried out through planted devices.

The MQM, however, has vowed to not bow down to the terrorists. Speaking to DawnNews, the party's leader, Haider Abbas Rizvi said that MQM has been targeted by forces which do not wish to see it coming into power. "We will continue with our election campaign and no one can deter us from our fundamental right of partaking in polls," he said.

“It’s sheer brutality,” MQM chief Altaf Hussain said. “Our morale is high and we will not surrender to the evil forces of extremism and terror. It’s so unfortunate that despite consistent attacks, no credible move has been witnessed against terrorists from the government, administration and security forces.”

The outlawed TTP has vowed to target the secular political parties of the country, naming Pakistan People's Party (PPP), Awami National Party (ANP) and MQM in the run up to the coming general elections.

The historic May 11 polls will witness the first ever democratic transition of power in Pakistan.