Officials in northwestern Pakistan say a blast at a political rally has killed at least four people. Officials say at least 12 people were wounded in the explosion Monday in the Batgram district.

Authorities say a senior member of the Pakistan Muslim League-Q Party was scheduled to attend the gathering, but was not at the site at the time of the explosion.

Elsewhere in Pakistan, an explosion has ripped through an army weapons depot near Islamabad, wounding at least three people.

The cause of the blast was not immediately known.

Militants linked to al-Qaida and the Taliban have stepped up suicide and bomb attacks across Pakistan since the killing of Osama bin Laden by U.S. Navy Seals in early May.