Police said more than 10 people were also wounded in the January 10 explosion, which took place during evening prayers at a mosque in a satellite town of the capital of Balochistan Province.
A deputy superintendent of police was among those killed.
Some of the wounded were said to be in a critical condition.
No one immediately claimed responsibility for the attack.
Resource-rich Balochistan, which borders Afghanistan and Iran, has been plagued by sectarian violence, Islamist militant attacks, and a separatist insurgency that has led to thousands of casualties since 2004.
On January 7 in Quetta, a bomb blast hit a paramilitary force vehicle, killing two troops.