BAGHDAD, Iraq — A Sunni driver lures Shiites into a van by promising jobs — then blows it up, killing 53 people. Sunni gunmen spray bullets and grenades at shoppers, not caring that they include women and children. Shiite death squads roam Baghdad streets, singling out and slaughtering Sunnis.

The new unity government of Shiites, Sunnis and Kurds was supposed to bring Iraqis together. Instead, sectarian bloodletting is spiraling out of control.

In the last two days alone, more than 120 people were killed in two spectacular examples of Sunni-Shiite violence — 53 in the suicide van bombing Tuesday in Kufa and 50 in the massacre Monday in the market in Mahmoudiya.

Since then, at least 19 more have been slain in Mahmoudiya in what police say were reprisals for the market massacre.

American officials had hoped the unity government, which took office May 20, could curb sectarian attacks by promoting cooperation between the sects. It promised to disband the Shiite militias and persuade Sunni insurgents to lay down their arms, so that U.S. troops could go home.

But unity in parliament has not been translated into peace on the streets. Lawmakers elected on religiously based tickets find it difficult to restrain their constituents, whose lives are under constant threat by the rival religious group.

With the government unable to protect them, people put their trust in religious-based militias. The killings continue and the government loses respect with every mass killing. Instead of withdrawal, the top U.S. commander, Gen. George Casey, said last week that more U.S. troops may take to the streets if Iraqi forces cannot cope with the rising violence.

Prime Minister Nouri al-Maliki may yet be able to reverse the slide. But public confidence is waning. His much-heralded security plan for Baghdad — which includes 50,000 police and troops operating checkpoints and patrolling the capital — is widely perceived as a failure.

The United Nations reported Tuesday that nearly 6,000 civilians were slain across Iraq in May and June, a spike that coincided with rising sectarian attacks. The report said 2,669 civilians died in May and 3,149 in June — the first full month of the al-Maliki government.

U.S. officials blame much of the sectarian crisis on the legacy of Abu Musab al-Zarqawi, leader of al-Qaida in Iraq until he was killed in a U.S. airstrike June 7. The Jordanian-born al-Zarqawi considered Shiites heretics and collaborators with the Americans and sought to promote civil war by repeated attacks on Shiite civilians.

"Terrorists have adapted by exploiting Iraq's sectarian fault lines," U.S. Ambassador Zalmay Khalilzad told a Senate committee last week. "Sectarian violence has now become THE significant challenge to Iraq's future."