Saher Gul was chalking a long division lesson on the blackboard of his two-room village school. Twenty-five boys, ages 9 to 19, were sitting cross-legged on the dirt floor. Suddenly the earthen walls and ceiling exploded and collapsed, smothering the class in a mountain of rubble.

Sher Mahmad was chatting with friends in the dusty village square when he heard the explosion. He sprinted toward the school, he said, where his son and four other young relatives were studying. Everyone dug frantically at the dirt, trying to reach the students before they suffocated.

"Who would do such a thing? This is against Islam, against our religious law, against all humanity," said Mahmad, a farmer in this drought-baked hamlet in Paktia province. Mahmad's son and Gul, the teacher, survived, but nine boys and a teacher died when a bomb detonated in the schoolyard last Saturday afternoon.

The circumstances of the attack remain confused, and possible motives abound. The village is remote, and news of the blast was initially obscured by a high-profile terrorist bombing last Sunday in Kabul, the capital, 90 miles north. Three Americans and at least seven Afghans were killed when a car bomb detonated outside a U.S. security company's office.

But in some ways, the bombing of the tiny Mullah Khel school was both more horrifying in its targeting of children and more alarming in its implications for Afghan society. The country, just emerging from 25 years of bloodshed and ideological tumult, is struggling to find a peaceful postwar balance between conservative tradition and modernizing progress.

The Taliban, an extremist Islamic militia that ruled most of Afghanistan from 1996 to 2001, has claimed responsibility for the Kabul bombing and has vowed to sabotage the country's movement toward political and social change by attacking foreigners, aid projects, schools for girls, government facilities and anyone working to promote October's presidential elections.

The bombed school is located in Zurmat, a troubled district that was once a stronghold of the Taliban and where support for the Islamic militia still exists. During Taliban rule, officials said, the Mullah Khel school was a Koranic academy, or madrassa, which taught Islamic studies to boys who lived on the premises.

After the collapse of the Taliban, the school continued offering morning Islamic lessons for local boys. But two months ago, with support from a foreign-funded agency called the Afghan Primary Education Program, it added an afternoon curriculum of English, math and other subjects taught in regular public schools.

Mullah Khel did not teach girls, and there are no elementary schools for girls in the village or nearby. In the past year, suspected Taliban militants have threatened rural girls' schools and set fire to several at night, but this was the first deadly attack to occur while a school was in session.

"Those who did this want to keep Afghanistan from education, to close the doors to progress. They don't know God, they only know money and destruction," said Mohammed Hashim, the police chief in Zurmat. He described the district as a "difficult and dangerous area. It was a major Taliban base. The people may not support them but they don't support us either," he said.

A second possible motive was the school's link to the election.

In recent months, the teachers at Mullah Khel had been involved in helping men and women register to vote, and some residents speculated that this could have made it a target for extremist violence.

But Gul, 26, who was at home Tuesday recovering from minor injuries, and a variety of older community leaders said everyone in the area was enthusiastic about both the afternoon classes and the chance to participate in elections.

"I cannot imagine who would kill these innocent children. All the tribal elders supported our lessons and encouraged me to educate their sons," Gul said. "Everyone here understands the value of education. A teacher is like a candle for the community, but it can only spread light when it is lit."

Perhaps the most important clue to the attack is that a religious instructor at the school, Mohammed Nawab, is missing. The explosives were hidden in Nawab's motorbike, which was parked in the schoolyard. Nawab has been missing since the day of the attack, raising official and private speculation that he was either kidnapped by the bombers or part of their plot.

Three days after the blast, the twisted wreck of the motorbike still stood in the yard. The earthen perimeter of the compound had crumbled in several places; the roof and one wall of Gul's classroom were gone.

On a wall that was still standing was his blackboard with a few chalk marks and a torn map of the world.

Outside, in the village plaza, boys with bandages on their heads and arms swarmed around a visiting unit of U.S. Marines, who had arrived from a military post in the provincial capital, Gardez, to dress their wounds and hand out toys. Last Saturday, Afghan and U.S. troops were called to the area and administered emergency medical aid.

"The ceiling fell on me and then I was unconscious," said Mohammed, 9, whose nose was covered with a bandage. "When I woke up I thought someone had fired a rocket at the school. I saw the hands of some boys coming from the dirt, and some bodies. I was hurt, too. We were all buried under the wall."

Despite the villagers' insistence that the school had no enemies, several officials and professionals in the region said they were extremely wary of traveling in the Zurmat district. One doctor in Gardez said he could not safely drive an ambulance to Zurmat, and another health official said he kept secret any plans for staff members to travel to clinics in the district.

Residents also reported that two Afghans working for an aid agency had been ambushed and killed by gunmen on the road from Gardez to Zurmat in July. Hashim, the police chief, said a personal dispute had triggered the incident, but he insisted that two trucks of soldiers accompany a reporter to visit the bombed school, about five miles off the same road.

Among the families of Naik Nam, the bombing has left a pall of fear and grief. The tribal elders are leathery, sun-baked men who rarely express emotion, but there were tears in the eyes of Gul Mahmad, 60, as he stood Tuesday over several freshly mounded graves at the edge of the village.

"We were so proud and happy when the school opened. None of us ever had the chance to get an education," said Mahmad, as a dusty desert wind whipped his turban cloth around him. "I had three grandsons in that school, and now two of them are dead. If I meet the people who did this, I will turn them over to the government, but I wish I could devour them myself."

Mohammed, 9, left, was injured when a bomb went off in the courtyard of his school in the village of Naik Nam.An Afghan policeman stands guard at the ruins of the village school in Naik Nam, which collapsed when a bomb on a motorbike outside exploded.