Baghdad, Iraq ? Insurgents foiled heightened security in Baghdad and killed more than two dozen people Saturday after an al-Qaida threat to avenge the death of Abu Musab al-Zarqawi, dealing a blow to the Iraqi government’s pledge to bring peace to the capital.

Eleven more Iraqis, including four in Baghdad, died in shooting attacks across Iraq.

U.S. troops, meanwhile, combed through the “Triangle of Death,” a predominantly Sunni Arab region south of the capital, looking for two soldiers missing since an attack Friday on a traffic checkpoint that also killed one of their comrades.

Maj. Gen. William Caldwell said four raids had been carried out since Friday’s attack and that ground forces, helicopters and airplanes were taking part in the search.

The soldiers came under attack at a traffic checkpoint next to a canal southwest of Youssifiyah, 12 miles south of Baghdad. The area is considered an insurgent hotbed.

“We are currently using every means at our disposal on the ground, in the air and in the water to find them,” Caldwell said.

The spree of bombings and mortar attacks in Baghdad was an embarrassment for Prime Minister Nouri al-Maliki, who ordered more police and army checkpoints for the city last week to restore security for its 5 million residents.

Market sellers clear debris after a mortar shell was fired at the Isterbadi market in the predominantly Shiite suburb of Kazimiyah in Baghdad. The blast killed at least four people and wounded 13. A series of bombings within a span of five hours Saturday killed more than two dozen people.

His Sunni Arab deputy prime minister, Salam Zikam Ali al-Zubaie, charged that the plan was not properly thought out and needed more work.

“I can say that I am not pleased with the way the Baghdad security plan began,” he told al-Jazeera television. “The Baghdad plan has begun, but it will need a year or more to finish.”

Al-Zubaie said the Interior Ministry, which is responsible for Iraq’s police forces, first had to be cleansed of people who might be responsible for “human rights violations.” Many Sunnis charge that Shiite-dominated security services have been infiltrated by Shiite militias blamed for sectarian violence.

“There are a lot of officials who were responsible for committing numerous acts of foolishness and many human right violations who are still in positions of responsibility,” al-Zubaie said.

Eight attacks killed at least 27 people and wounded dozens in the Baghdad area.

The violence included a suicide bomber who blew up his car as it was being towed near a police checkpoint in Mahmoudiya, south of the city, killing four civilians and injuring 15. The bomber had claimed his car broke down and hired a tractor to tow it while he rode inside, police Capt. Rashid al-Samarie said.

A mortar barrage also hit a residential area in Mahmoudiya, a predominantly Sunni town about 20 miles south of Baghdad, killing one civilian and wounding three.

In Baghdad itself, a mortar shell hit one of Baghdad’s best-known markets, in the predominantly Shiite suburb of Kazimiyah, killing at least four people and wounding 13, police said.

About a half hour later, two people died and 24 were wounded when a bomb left in a plastic bag exploded at an outdoor market where secondhand goods are sold in central Baghdad.

Police said a suicide bomber targeting an Iraqi army patrol near Wathiq Square in the same neighborhood killed seven people when he blew himself up.

A parked car bomb in southwest Baghdad killed six people and wounded 36, police said.

Three mortar rounds hit a popular market in northern Baghdad, killing two.

One other person died from a roadside bombing.