BAGHDAD, Aug. 14 — Four truck bombs killed at least 190 people on Tuesday in two villages in a Kurdish-speaking area near the Syrian border, destroying houses and sending hundreds of the wounded to at least six hospitals as far as 150 miles away, the Iraqi authorities said. Hours after the blasts, victims were still buried in dusty rubble as American helicopters ferried away the wounded. “Half the houses are completely collapsed because they were made from clay,” said Capt. Mohammed Ahmad of the Iraqi Army’s 3rd Division. He said scores of families were obliterated in the blast that wiped out a market and a bus station. Another Iraqi officer described the scene as apocalyptic: “It looks like a nuclear bomb hit the villages,” he said. The bombs — including at least one rigged to a fuel tanker — detonated in quick succession around 8 p.m. in Qahtaniya and Jazeera, two towns populated mostly by Yazidis, a Kurdish-speaking sect that mixes elements of Islam with the teachings of an ancient Persian religion. The group has long been a minority in Iraq, and after some Yazidis stoned a Yazidi woman to death for dating a Sunni Arab man in April, members of the sect became frequent targets of Sunni attacks. When a video of the Yazidi woman being stoned appeared on the Internet, gunmen stopped minibuses full of Yazidi laborers and killed 23 of them. Many Yazidis have recently moved to villages farther west, where they make up a majority. The deadly assault on Tuesday crushed the hope that there would be safety in numbers — especially near the border with Syria, which American officials have long described as an entry point for foreign fighters. The blasts capped one of the worst days of violence in months and raised further questions about whether the American military effort has pushed insurgents into less populated areas. The explosions also came only a few hours after Iraqi leaders met for lunch in advance of a “crisis summit” meeting to discuss how to solve their sectarian divisions and smooth out their knotted government. The gathering, like many before it, produced no results. An aide to President Jalal Talabani called the lunch “an icebreaker,” but Adnan Dulaimi, leader of the largest Sunni bloc, said nothing political was discussed. “It was only an invitation for lunch,” he said. “We didn’t engage in any negotiations.” American officials have been pushing Iraqi leaders to hammer out a grand compromise on several outstanding issues, from a new oil law to provincial elections. But in the midst of the continued stalemate — with the Shiite-led government of Prime Minister Nuri Kamal al-Maliki missing 11 cabinet ministers who have quit in protest — violence and the American effort to stop it continued to shudder through the country. In an attack on Tuesday that seemed destined to heighten political tensions, at least 100 gunmen in Iraqi Army uniforms kidnapped several senior Oil Ministry officials from their homes in a fortified government compound. The captives — the deputy oil minister, Abdul Jabar al-Wagaa, three department heads and one of the officials’ sons — were abducted from a guarded area that sits about 300 yards from an Iraqi Army checkpoint often manned with tanks. The motives for the kidnappings remained unclear. Mr. Wagaa, the most senior deputy minister, is a Sunni Muslim from Baiji, where Iraq’s oil refining is concentrated. Attacks by gunmen wearing army or police uniforms are typically attributed to Shiite militias that work within the security forces. But the Iraqi oil minister, Hussain al-Shahristani, said the abduction did not appear to be sectarian because at least two of the victims were Shiites. “The goal of this operation is to stop the work of the government and to damage the political process,” he told the state news channel, Iraqiya. Elsewhere in Iraq on Tuesday, a truck bomb in Taji, north of Baghdad, killed at least 10 people and destroyed a bridge on the main highway connecting the capital with northern cities like Mosul. Witnesses said the explosion destroyed the bridge, which was damaged in May by a car bomb, and sent several vehicles into a canal. Afterward, American and Iraqi divers could be seen trying to pull people out of the water. Military officials said the cause of a helicopter crash on Tuesday that killed five Americans in Anbar Province, west of Baghdad, was still under investigation. A statement said the dual rotor CH-47 Chinook went down “while conducting a routine post-maintenance-check flight.” Three American soldiers also died from a roadside bomb on Monday near Mosul, the military said in a statement. Two others died from attacks in western Baghdad, one on Tuesday, another on Monday. Meanwhile, in Diyala Province, roughly 10,000 American soldiers and 6,000 Iraqis continued to push through villages surrounding Baquba in what commanders described as a large-scale offensive aimed at Sunni extremists. The operation follows a major effort in June to seize control of Baquba, the area’s main city, from organizations like Al Qaeda in Mesopotamia, a homegrown Sunni Arab extremist group with some foreign operatives. Many gunmen fled when the American and Iraqi troops arrived in force. Military officials said the latest phase, named Lightning Hammer, began Monday and sought to attack the insurgents where they found refuge, especially among villages outside Baquba. “The Iraqi Army and Coalition Forces are committed to the people of Diyala, they are committed to fighting for the Iraqi people’s security,” said Maj. Gen. Benjamin Mixon, commander of Multinational Division North, which covers the area. “We will aggressively and persistently target Al Qaeda, an organization that brings nothing but hatred, destruction and disregard for the very foundation of the Iraqi peoples’ principles and faith.” Military officials did not say whether the truck bombings could also be a result of their efforts in other areas. Residents in and around Qahtaniya said the area held many members of Al Qaeda in Mesopotamia. Past operations have pushed insurgents to new locations only to return later, but it is not clear where the attackers on Tuesday were based. Reporting was contributed by Qais Mizher, Ahmad Fadam, Abdul Razzaq al-Saiedi, Khalid al-Ansary and Diana Oliva Cave from Baghdad, and Iraqi employees of The New York Times from Mosul.