Thirteen people were killed Wednesday in a suicide-bombing at a Shi'ite mosque in Rawalpindi, a city near the capital that hosts Pakistan's army headquarters.
The blast, which occurred shortly before midnight during a Shi'ite procession, followed two earlier bomb attacks that left a total of five Shi'ites dead in the country's largest city, Karachi.
The explosion also knocked out electrical power to the neighborhood, adding to the chaos, Express Tribune newspaper said in its online edition.
Besides the 13 fatalities, a score of people were injured in the attack.
The bomber walked into the procession and detonated explosives taped to his body, according to police sources cited by the Geo network.
The attacker was also carrying several grenades, the sources said.
Shi'ites, who make up about 20 percent of Pakistan's population, are preparing for the observance of the Ashura holiday on Nov. 24.
Though the day is also holy to Sunnis, it is especially significant for Shi'ites and anti-Shi'ite militants often take advantage of the occasion to mount attacks.
The Pakistani government announced a security high alert to extend through the Ashura holiday. EFE