A cycle of tit-for-tat killings between Pakistan's Sunni and Shi'ite communities threatens to rip open sectarian fault lines.
After radical Sunni ideologue Aurangzeb Farooqi survived an attempt on his life that left six of his bodyguards dead, he called on his followers to close ranks against Karachi's Shi'ites.
The Shi'ite minority are braced for a new chapter of persecution following a series of bombings that have killed almost 200 people in Quetta since the beginning of the year.
While Quetta grabbed the world's attention, a spate of murders in Karachi has led to 80 Shi'ite deaths in the past six months.
In return, a number of hard-line Sunni clerics and followers of Farooqi have also been killed.