The blasts went off as worshippers were attending Friday prayers in Khanaqin, a mixed Shi'ite-Kurdish town northeast of Baghdad, near the border with Iran.
The blasts occurred several hours after two car bombs exploded in Baghdad, killing at least six people and injuring some 40 others.
A U.S. soldier, identified only as Sergeant Carwin, told the Reuters news agency the bombers in the Baghdad attacks targeted the Al-Hamra hotel, which is near an Interior Ministry building.
"Both trucks blew up right here, did tremendous damage to this apartment building right here and destroyed this apartment building over here, wounding scores of innocent Iraqi people," Carwin said.
Meanwhile, the U.S. military today said U.S. and Iraqi forces have killed 32 insurgents after more than 50 fighters started a series of attacks against military outposts in Al-Ramadi, west of Baghdad. A U.S. military statement says one U.S. Marine and an Iraqi soldier were wounded in the fighting.