Bomb blast kills dozens in Pakistan

A suspected suicide bomber attacked Shi'ite Muslims as they were leaving a mosque in Pakistan's commercial capital on Sunday, killing at least 45 people, in another signal Sunni militants are escalating sectarian attacks.

A Pakistani man, who was injured in a bomb blast, is brought to a hospital in Karachi, Pakistan, Sunday, March 3, 2013. Pakistani officials say a bomb blast has killed dozens of people in a neighborhood dominated by Shiite Muslims in the southern city of Karachi. (AP Photo/Shakil Adil)

Pakistani men carry the body of a man from the site of a bomb blast in Karachi, Pakistan, Sunday, March 3, 2013. Pakistani officials say a bomb blast has killed dozens of people in a neighborhood dominated by Shiite Muslims in the southern city of Karachi. (AP Photo/Fareed Khan)

Pakistani medics carry the lifeless body of a man from the site of a bomb blast in Karachi, Pakistan, Sunday, March 3, 2013. Pakistani officials say a bomb blast has killed dozens of people in a neighborhood dominated by Shiite Muslims in the southern city of Karachi. (AP Photo/Fareed Khan)

Pakistani medics and civilians gather at the site of a bomb blast in Karachi, Pakistan, Sunday, March 3, 2013. Pakistani officials say a bomb blast has killed dozens of people in a neighborhood dominated by Shiite Muslims in the southern city of Karachi. (AP Photo/Fareed Khan)

PAKISTAN-UNREST-KARACHI

People gather on the site of bomb blast in Karachi on March 3, 2013. A bomb attack in Pakistan's largest city Karachi on Sunday killed at least 23 people, including women and children, and wounded 50 others, police said. AFP PHOTO/ASIF HASSAN (Photo credit should read ASIF HASSAN/AFP/Getty Images)

Pakistani children, who were slightly injured in a bomb blast, are brought to a hospital in Karachi, Pakistan, Sunday, March 3, 2013. Pakistani officials say a bomb blast has killed dozens of people in a neighborhood dominated by Shiite Muslims in the southern city of Karachi. (AP Photo/Shakil Adil)

Pakistani check the site of a bomb blast in Karachi, Pakistan, Sunday, March 3, 2013. Pakistani officials say a bomb blast has killed dozens of people in a neighborhood dominated by Shiite Muslims in the southern city of Karachi. (AP Photo/Fareed Khan)