At least 15 people have been killed in a suspected suicide bombing outside a polio vaccination center in the southwestern Pakistani city of Quetta.
The explosion took place on January 13 as police officers were gathering to accompany polio workers for the third day of a vaccination campaign in the Balochistan Province, where Quetta is the capital.
Officials said that most of the dead were police officers. Some 20 people were also injured.
Jundullah, a splinter group of the Pakistani Taliban which has pledged loyalty to Islamic State, claimed responsibility for the attack.
Teams working to immunize children against polio in Pakistan have been the target of many deadly attacks by militant groups in recent years.
Militants say the polio vaccination campaign is a cover for Western spies or a conspiracy to sterilize Pakistani children.
Pakistan and Afghanistan are the only two countries where the disease is still endemic.
Meanwhile, attackers on a motorcycle lobbed grenades and opened fire at Pakistan's independent ARY news channel in Islamabad on January 13, wounding an employee.
ARY said the attackers left behind a leaflet -- purportedly from the Islamic State extremist group -- warning of more attacks against media.