Pakistani police officers collect evidence from the site of a suicide bombing in Quetta, Pakistan, on Sunday, Dec. 30, 2012. A suicide bomber driving a pickup truck packed with explosives rammed into a bus carrying Shiite Muslim pilgrims in the country's southwest, killing 19 people, a government official and eyewitnesses said. (AP Photo/Arshad Butt)

Photo by: Arshad Butt

Pakistani police officers collect evidence from the site of a suicide bombing in Quetta, Pakistan, on Sunday, Dec. 30, 2012. A suicide bomber driving a pickup truck packed with explosives rammed into a bus carrying Shiite Muslim pilgrims in the country's southwest, killing 19 people, a government official and eyewitnesses said. (AP Photo/Arshad Butt)