BAGHDAD, Iraq — Gunmen seized two dozen Shiites from a bus station after separating them from the crowd in a predominantly Sunni area yesterday, killing them and dumping their bodies in a nearby village — the latest in a series of brazen attacks.

Prime Minister al-Maliki appealed for unity and warned the nation’s future was at stake. “We all have the last chance to reconcile and agree among each other on avoiding conflict and blood. If we fail, God forbid, I don’t know what the fate of Iraq will be,” he told parliament.

The gunmen arrived in several cars at the bus station in Muqdadiyah, about 60 miles northeast of Baghdad, about 6 a.m., forcing the captives into four vehicles they commandeered at the scene, officials said.

The bloodied bodies of the victims, who were handcuffed, blindfolded, and shot in the head, were found behind a pile of small rocks near the main street of Azham village, police said.

Some of the dead had their hands clasped. Relatives wept over loved ones, with one man leaning over an open coffin and kissing the hand of a victim.

Major General Ahmed al-Awad, commander of the Iraqi army’s 5th division, told state-run television the attackers separated Shiites from Sunnis, then took the Shiites to the nearby village of Ballour, an account supported by witnesses.

The rural area, which is just north of the site where Al Qaeda in Iraq leader Abu Musab al-Zarqawi was killed, has a slight Sunni majority and is in a province where tensions between Shiites and Sunnis run high.

The Iraqi army staged an operation in the area last week against insurgents, drawing complaints from Sunni political leaders that villages had been surrounded and cut off from food and medicine.

The massacre was part of a surge in sectarian violence that has killed more than 160 people since Sunday, when Shiite gunmen rampaged through a Baghdad neighborhood killing Sunnis.

Yesterday’s attack coincided with an unannounced visit to Iraq by Defense Secretary Rumsfeld, who said the new Iraqi government is not yet ready to decide on security issues that will determine the pace of American troop reductions this year.

America had hoped that a unity government of Shiites, Sunni Arabs, and Kurds could calm the tensions and persuade insurgents to lay down their arms so that America and its coalition partners could begin withdrawing troops.

But more than 1,607 Iraqis have been killed and nearly 2,500 wounded since Mr. Maliki’s government took office May 20, according to an Associated Press count.

The top American commander in Iraq, General George Casey, said “terrorists and death squads” are mainly responsible for the heightened sectarian violence in the capital, and he pledged to provide whatever American forces are needed to avert civil war.

General Casey told reporters that Al-Qaeda is trying to “demonstrate that they are still relevant” after the June 7 killing of Zarqawi.

“What we are seeing now as a counter to that is death squads, primarily from Shiite extremist groups, that are retaliating against civilians,” the general said. “So you have both sides now attacking civilians, and that is what has caused the recent spike in violence here in Baghdad.”

The prime minister met with the American officials and told them he had high hopes for his 24-point national reconciliation plan, which includes an amnesty for some insurgents, calling it “a historic opportunity for us to cross toward stability,” according to remarks released by his office.

At least 21 other violent deaths were reported across the country, including a soldier who was killed when a suicide car bomber struck an Iraqi army checkpoint in the western Baghdad neighborhood of Amariyah.

A suicide bomber also walked into a restaurant and blew himself up in the southeastern Sunni-Shiite neighborhood of New Baghdad, killing eight people and wounding 30, a local police chief, Colonel Ahmed Aboud, said.

Police in the northern Baghdad neighborhood of Azamiyah were ambushed when they arrived to collect six bodies that had been found; one policeman was wounded.

Despite the sectarian bloodshed, fliers purportedly signed by Al Qaeda-linked umbrella group the Mujahedeen Shura Council were circulated in a predominantly Sunni area north of Baghdad, urging Shiite families not to flee and warning people not to hurt members of the majority sect.

In a positive sign, the Iraqi Accordance Front, the largest Sunni bloc in parliament, lifted its legislative boycott and attended yesterday’s session. It thanked the parliament for its help in seeking the release of kidnapped legislator Tayseer al-Mashhadani and called for a new spirit of cooperation.

In his speech to parliament, Mr. Maliki urged his countrymen to unite behind his administration’s efforts to stem the bloodshed.

“It is not only the government that should be responsible. You chose the ministers and the prime ministers. You should not stand up and criticize the government,” Mr. Maliki said, an apparent reference to some lawmakers who criticized the government because of the bad security situation.

He also said insurgents have plans to take control a large swath of western Baghdad to divide the capital of 6 million people, “but be sure that Iraqi forces are capable of repulsing them and have started striking them.”