Officials in northwest Pakistan say a suicide bomber has targeted a Shi'ite mosque, killing at least 21 people and wounding more than 30.
Authorities say the blast in the town of Hangu happened as Shi'ites were leaving Friday prayers, but the casualties also included worshippers from the nearby Sunni mosque.
Hangu has long been a flashpoint for violence against minority Shi'ites, who make up an estimated 20 percent of Pakistan's population. Sunni Muslim militants view Shi'ites as heretics.
There was no immediate claim of responsibility for the attack.
Hangu is near Pakistan's tribal belt on the Afghan border where Taliban and al-Qaida militants have carved out strongholds.
Human Rights Watch said in its annual global report Thursday that religious minorities in Pakistan, such as Shi'ite Muslims, continue to face persecution. The report said the government has failed to provide protection to those threatened or to hold extremists accountable.