The violence erupted with a suspected suicide attack on Shiites in Hangu , in the northwestern part of the country , as they celebrated Day of Ashura .
Sectarian violence marred the holiest day of the Shiite calendar .
The violence erupted with a suspected suicide attack on Shiite in Hangu , in the northwestern part of the country , as they celebrated Day of Ashura .
Sectarian violence marred the holiest day of the Shiite calendar .