Rescue workers were sifting through rubble in an attempt to find survivors from the attack in the town of Tal Afar, near the Syrian border. About 30 people were injured, police said.
Meanwhile in Baghdad, a roadside bomb killed nine civilians and wounded eight during rush hour on Monday morning, police said.
Overnight, police in the town of Baquba – in Diyala province, where US and Iraqi forces have mounted an offensive against insurgents over the past several weeks – found 60 decomposing corpses in tall grass.
In Baghdad, police said they had recovered 18 bodies.
The violence came as Iraqi politicians prepared for talks this week to restore a unity cabinet that was designed to reduce sectarian strife by including members of all communities but hit a crisis last week when the main Sunni Arab group pulled out.
Parliament went on recess last week without having passed laws, such as a bill to share Iraq's oil wealth, which Washington considers vital to ending sectarian violence by promoting national reconciliation.
US Defence Secretary Robert Gates has criticised the parliamentary recess with some of the harshest words Washington has directed at Iraq's leaders.
"I said 'for every day that we buy you, we're buying it with American blood. The idea of you going on vacation is unacceptable'," Gates said on NBC's Meet the Press.
Parliament cannot pass the laws unless they are first drawn up by the government, which is stalled after the Sunni Arab bloc's pullout.
Prime Minister Nuri al-Maliki, a Shi'ite who has led the unity government since taking power last year, announced on Sunday he would not accept the resignations of the six Sunni cabinet ministers who quit last week.
But the Sunni ministers' Accordance Front bloc said they would quit anyway unless Maliki met their demands, which include more influence over security policy.
Front leader Adnan al-Dulaimi said Maliki was running "an unsuccessful sectarian government that intended to frustrate the political process".