Officials in northwestern Pakistan say a bomb blast near a Shi'ite religious procession has killed at least five people.

Authorities say about 70 people were wounded in the explosion Sunday in Dera Ismail Khan, where an explosion Saturday also targeted Shi'ites. Seven people, including three children, were killed in Saturday's blast.

Police say the bomb that exploded Sunday had been planted in a shop.

There has been no claim of responsibility for the latest attack.

The bombings come as Muslims observe the holy month of Muharram, the first month of the Islamic calendar. Sunni extremists have targeted minority Shi'ites in the past during Muharram.

Authorities have tightened security across Pakistan to guard against possible attacks on Shi'ite gatherings during Muharram. Pakistan has temporarily suspended mobile phone service in major cities to prevent bombings, which are often triggered by cell phones