KARACHI: Four people were killed and at least 42 others had been injured in a blast in Karachi's Federal B Area locality on Tuesday, DawnNews reported.

The blast, which took place near Federal B Area's Aisha Manzil, was heard as far as Karachi's Numaish area. The injured were shifted to hospitals and police had reached the site of the explosion that reportedly took place near a furniture market.

The bomb appeared to have been planted on a motorbike parked within the vicinity of the blast site. Police sources said that the explosion was caused by a  remote-controlled bomb.

Sources said that some of the injured are in critical condition and that one of the people who was killed was a Muttahida Qaumi Movement (MQM) worker.

The outlawed Tehrik-i-Taliban Pakistan has claimed responsibility for the attack on the rally in Karachi and has warned that it will carry out more attacks on MQM workers and leaders.

The TTP spokesman Ehsanullah Ehsan speaking to Dawn.Com said that their activists had targeted the MQM workers and that the attack was a warning, stating that more attacks are likely to come after it.

He also cautioned the general public to avoid participating in MQM and Awami National Party (ANP) rallies, otherwise they would be responsible for their losses.

The blast has been strongly condemned by a number of political figures, including President Asif Ali Zardari, Prime Minister Raja Pervez Ashraf, MQM chief Altaf Hussain and PML-N chief Nawaz Sharif.

The MQM's Coordination Committee announced that a day of mourning will be observed on Wednesday in the aftermath of the explosion. They said that transport and business activities will not be suspended during the day of mourning.

Tuesday's explosion took place days after a powerful blast inside an inter-city bus near Karachi’s Cantonment Railway Station killed at least six people and left at least 50 others, including women and children, injured.