Mortar shells and bombs targeted worshippers shortly after noon prayers on Friday at two mosques north of Baghdad, killing nine people and wounding more than two dozen others, police said.

It's unclear what prompted the attacks, but violence has been on the rise ahead of provincial elections set for Saturday. The vote is for local officials in several provinces across the country, including the capital, Baghdad. Authorities have pledged to bolster security for the elections.

Police said the first attack occurred as worshippers left the Sunni mosque of al-Muthana in Khalis, a former stronghold of the Sunni insurgency about 50 miles north of Baghdad. Seven people were killed and 14 others were wounded when mortar shells destroyed the mosque.

Later, in the city of Kirkuk, a roadside bomb exploded among Shiite worshippers as they were heading home after prayers at the al-Tamimi mosque. Police said two worshippers were killed and 14 others were wounded.

Medics in nearby hospitals confirmed the dead toll. All officials spoke on condition of anonymity because they were not authorized to speak to reporters.

The new violence came a day after a suicide bombing attack on a Baghdad cafe killed 32 people and wounded dozens. The rare evening attack struck the third floor of a building in the predominantly Sunni neighborhood of Amiriyah while it was packed with young people enjoying water pipes and playing pool.