The growing horror in a city where 500 children were kidnapped by Boko Haram

Construction workers are painting over the Boko Haram graffiti. Plywood frames are rising in the place of homes destroyed by grenades and bombs. Thousands of refugees are returning. On the surface, this city once occupied by Islamist extremists is slowly returning to normal.

Except for one horrifying fact: Hundreds of children are missing.

Most of them were seized by Boko Haram in the fall of 2014. Months earlier, in April, the militants had carried off 276 schoolgirls from the town of Chibok, a kidnapping that became the subject of a global campaign known by the hashtag #BringBackOurGirls. But there has been little attention to the lost children of Damasak. Residents say they total more than 500. All but a handful are still unaccounted for.

In the ruins of the city, everyone seems to be missing a son or a daughter, a brother or a sister. Outside the mud walls of his roofless house, Aji Bakar holds a picture of his chubby-cheeked 9-year-old grandson, who was kidnapped from his classroom in September 2014.

"Our senators and governors are negligent," he said. "Why can't they find him?"

Fatima Kyari sits down next to Bakar. Her son, too, is missing.

"When Boko Haram fled from Damasak, they took him," she says angrily.

Hearing that journalists are asking about the city's vanished children, more people join the circle, under the half shade of a thorny tree.

Yusuf Aisami lost his 12-year-old brother. Umara Yakami lost his 10-year-old son.

Some details about the mass kidnappings had trickled out in the months after they occurred. Human Rights Watch had reported in 2015 that at least 300 elementary school students had been seized in Damasak on Nov. 24, 2014, in what it called "the largest documented school abduction by Boko Haram militants."

Many of the children had been held at the school by Boko Haram until March 2015, when a multinational military force converged on Damasak, part of a major offensive to defeat the guerrillas. The insurgents fled with the children - the last time they were seen.

Two years later, many residents have now returned from years living as refugees in neighboring Niger. Others had fled to remote villages in Nigeria. Some, like Bakar, spent time in the forest, living off wild fruit and running each time they heard Boko Haram fighters.

The residents have come back to find their houses burned and their shops looted. The Nigerian government, buoyed by a large international assistance package, has vowed to restore normalcy. But the least normal thing about Damasak - its hundreds of missing children - remains unresolved.

"For now, we haven't received any information about where they are, or if they are still alive," said Maj. Mohammed Kaigama, the deputy military commander in the city.

Residents have submitted the names of more than 500 missing children to local authorities, but the families have received different versions of that disappointing response.

"After two years, parents of the missing children are desperate for information, but have received little more than rumors," Human Rights Watch said in a recent statement.

Meanwhile, the Chibok girls have been the focus of protracted negotiations, including a deal mediated by the Swiss government that led to the release of 21 of the students in October. President Muhammadu Buhari has pledged again and again to free the rest.

"We really wonder about it - why those girls but not our children?" Bakar asked.

Thousands of other Nigerians went missing over the past decade, as Boko Haram gained strength and territory across Nigeria's northeast, particularly in the state of Borno, which is about the size of Belgium. Many of the kidnapped girls and women were forced into marriage with the fighters. Other young women mysteriously reappeared as suicide bombers years later. The boys sometimes became child soldiers. The men were often killed immediately.

It's only now, when cities such as Damasak are being restored, their residents pouring back, that the scale of Boko Haram's ravages are becoming known, as people begin to tabulate the missing. Tuesday was the first time foreign journalists had visited the city of 105,000 people in at least two years.

It offered a glimpse of the surreal afterlife of Boko Haram's occupation. A young boy, seemingly without relatives, stood petting a horse surrounded by decimated houses. A girl, no older than 10, had drawn a manic cityscape with a piece of charcoal on the wall of an abandoned building. When a man took a step toward her, she shuddered.

But the missing were Damasak's most dystopian feature. Families were removing the ashes and rubble from their homes, but there were now empty rooms, where children once slept. Many had gone to Zanna Mobarti Primary School. Others were studying the Koran in religious schools when they were abducted. Some extended families lost more than a dozen children.

Bakar pointed to a place next to a mud wall that once was home to his grandson, Ajimi Dala.

"We don't know if we'll see him again," he said.