Scores were killed as two bomb blasts ripped through crowds who had gathered in Karachi to welcome home former Pakistani Prime Minister Benazir Bhutto.

Witnesses described a "hellish" scene in the aftermath the bombings that targeted a truck carrying Ms Bhutto.

There was carnage and confusion after the blasts as police struggled to move the dead and injured from the streets. Everywhere the wounded cried out for help.

The injured - including children - were ferried to hospitals by whatever means possible. Some were simply carried in for treatment.

For supporters of Ms Bhutto's Pakistan Peoples' Party, the day started with joy over her homecoming, but turned to horror as the scale of the atrocity unfolded.

Ms Bhutto escaped unhurt after the blasts and was quickly taken from the scene.

Critics say there was not enough security, and that combined with the fact her convoy was barely able to move because of large crowds made it easier for attackers to strike.

Earlier on Thursday, hundreds of thousands lined the streets to welcome Ms Bhutto back from self-imposed exile. She chose not to use a bullet-proof screen provided for her.

Questions are being asked about the wisdom of her much-publicised journey from Karachi airport to the shrine of Pakistan's founding father, Mohammed Ali Jinnah.

A torn poster of Ms Bhutto symbolises a day that ended in destruction.