Police say a bomb blast has killed three children and wounded 18 people at a Shiite Muslim procession in northwestern Pakistan, The Associated Press reported.

Police official Rashid Khan said the bomb struck the procession Saturday, Nov 23, in the city of Dera Ismail Khan, which is located near South Waziristan tribal region.

On Sunday, Shiites in Pakistan will celebrate Ashoura, a feast on the 10th day of the holy month of Muharram.

Pakistan has suspended mobile phone service in major cities for two days to prevent such bombings, which often use cellular phones as detonators.

Sunni extremists often target Shiites during Muharram, especially on Ashoura, when Shiites commemorate the seventh century death of Imam Hussein, the Prophet Muhammad's grandson.

The Sunni-Shiite schism over the heir to the Prophet Muhammad dates back to that time.