In the year since a teenage gunman strode into Robb Elementary School in Uvalde and killed 19 fourth graders and two teachers, the building has stood empty, its windows boarded over, its students dispersed to other campuses with little chance to maintain the bonds they once shared.

That was poised to change on Saturday, as residents of the small town in South Texas prepared to break ground for a new elementary school in place of the one that became the scene of one of the worst school mass shootings in American history.

“Something horrible happened here,” said Eulalio Diaz Jr., the co-chair of a foundation dedicated to constructing the new campus, the first to be built in the town since 1985. “The new school, it’s a symbol of moving forward. We will always remember what the new school means. It’ll be a bright light in a dark time.”

Emotions remain raw 17 months after the tragedy, and many in this majority Latino community are still seeking explanations for why it took law enforcement officers from several agencies more than an hour to confront the gunman in a pair of connected classrooms where he was holed up with students, many of them dead or dying.

Robb Elementary is slated to be demolished as soon as the numerous lawsuits and law enforcement investigations are concluded and there is no more need to secure evidence from the crime scene.

The new school — 120,000 square feet, over two floors — will include a number of safety measures to prevent the entry of an intruder and facilitate a police response, Mr. Diaz said.

Unlike Robb Elementary — which was built in the 1950s, an era when open access and many doors were not only welcomed but also expected — the new school will be relatively restrictive. Staff members will need badges to open the doors, and there will be fewer exterior doors, said Tessa A. Benavides-Cooper, a spokeswoman with the Charles Butt Foundation, one of the donors to the project. Visitors will be asked to wait in a vestibule where a staff member behind a secure door will assess whether the person should be buzzed in.

“The school will have multiple levels of security,” Ms. Benavides-Cooper said.

The school will have 9-foot-tall gates, a new road to help the police and emergency medical workers access the school grounds, fencing around play areas and other measures that will not be obvious.

The new campus will also feature two playgrounds, one of them for children with special needs, an air-conditioned gym and a large outdoor courtyard.

Architects said they wanted to make sure the décor included cheerful elements that would also recognize the large Mexican American community in Uvalde, including colors of papel picado, the traditional Mexican folk art that features multicolor sheets of paper.

They also did not want to forget about the victims. There are plans to build a metal tree near the school library with two big limbs and 19 smaller ones to memorialize the two teachers and the children who died.

Traditionally, the school district would have had to hold a bond election to pay for a new building, a process that can take years.

Instead, the facility will be funded solely by the foundation Mr. Diaz co-chairs, the Uvalde CISD Moving Forward Foundation, which includes community members from around the South Texas region.

The foundation initially raised $10 million from the grocery store chain H-E-B and its owners. Other companies, including Huckabee Inc. and Joeris Construction, donated services. As of October, the foundation had raised about 75 percent of the about $60 million needed to build the new campus. Construction was expected to begin this fall, said Tim Miller, the executive director.

The school does not yet have a name. By the time it opens in 2025, many of the former students at Robb Elementary will be in junior high school. It will welcome a new crop of about 800 of second, third and fourth graders.