The dead included five students from the seminary where the bomb exploded as people gathered to attend a degree ceremony. The 10 others were teachers, employees and relatives of the students, police said.

"Seven more critically injured died in hospitals overnight. A total of 30 people, including students, were wounded in the blast," Abdur Rahim Khokhar, a local police official, told AFP.

Khokhar warned that the death toll could still rise further.

Police said six kilograms (13 pounds) of explosives were planted on a bicycle, parked outside the seminary and covered with garlands.

There was no immediate claim of responsibility for the attack. Quetta is the capital of Baluchistan province, which borders Afghanistan and Iran.