The attack occurred shortly after 1 p.m. at a mosque inside a government-run religious school, shattering windows and pocking the walls with shrapnel and splattered blood. Bits of flesh and pools of blood lay all around as rescue workers tended to the wounded.

The school, which houses students aged 4-18, has separate mosques for Sunni and Shiite Muslim worshippers. Witnesses said the school had been let out early, as it normally does on Fridays.

Most of the victims were adults who came to the mosque for prayers.

A list posted outside Karachi's Civil Hospital recorded nine deaths from the blast, and 45 injured. Another casualty and five more injured were taken to the city's Jinnah Hospital, an official there said.