Pakistani army soldiers stand guard during a Shiite Muslim religious procession in Rawalpindi on December 24, 2013
At least seven people were killed and 28 injured in twin bomb blasts targeting Shiite Muslims in Pakistan's port city of Karachi on Tuesday, officials said.
The blasts occurred as Shiites observed the 40th day of mourning of the martyrdom of Hussain, the grandson of prophet Mohammad.
The first blast came near the wall of a Shiite mosque in Orangi Town, a bustling western suburb, followed by another powerful explosion a short distance away.
"Both the bombs were detonated with brief intervals, the second was quite fatal," Chaudhry Asad, a senior police officer told AFP.
City police chief Shahid Hayat told reporters that both were timer devices.
A third bomb exploded near Numaish Chowrangi in the eastern district but no casualty was reported. The spot was supposed to be on the route of the Shiite procession.
Pakistan has seen a steep rise in sectarian violence after a deadly clash between Sunni and Shiite Muslim groups in the cantonment city of Rawalpindi in November that left around a dozen people dead.
Authorities switched off cell phone services in dozens of cities across the country on Tuesday as a security measure, while 10,000 soldiers were put on standby.
Pakistan is rife with sectarian clashes, with Sunni militant groups linked to Al-Qaeda and the Taliban often attacking gatherings by Shiites, who constitute some 20 percent of the country's population.