A terrifying pre-dawn disaster in the Philippines left one person dead and at least 21 others trapped after a nine-story building under construction suddenly collapsed, sending concrete, steel and scaffolding crashing into a busy city neighborhood.

The building, located in Angeles City in Pampanga province, came down around 3 a.m. on Sunday, May 24, while many construction workers were reportedly sleeping inside.

Authorities said the people still trapped are mostly workers buried under massive concrete slabs, iron bars, aluminum scaffolding and piles of twisted debris.

One person killed in the collapse was identified as a 65-year-old Malaysian tourist. Officials said he had been staying at a nearby hotel that was struck by debris when the unfinished building gave way.

The collapse happened in a crowded part of Angeles City, an area filled with hotels, cafes, spas, homes and businesses. The city was once home to one of the largest U.S. Air Force bases before it closed in the 1990s.

Rescuers have been racing against time to find survivors in the rubble.

Five trapped people were confirmed to be alive, according to officials, but they could not immediately be pulled out because of the dangerous conditions. Two of them were reportedly able to communicate with rescuers, while the condition of the others remained unclear.

City information officer Jay Pelayo described a nightmare scene, saying the building’s walls and surrounding scaffolding buckled and buried people beneath huge pieces of debris.

“There are big chunks of concrete, and we need equipment to lift them up,” he said. “That is what’s challenging for the rescue right now.”

Officials said the building was planned as a nine-story condo-hotel, with a swimming pool being built on what planning records described as the 10th floor.

At least 24 construction workers either escaped from the ground floor or were rescued after the collapse. Many others were not so lucky.

More than 700 rescuers were called in as desperate families gathered nearby, waiting for any word about their missing loved ones.

For 18-year-old student Joamel Angcao, the disaster became a personal nightmare. She told the Associated Press that she and her siblings were waiting for updates about their parents, who had been working at a food and coffee cart beside the building when it collapsed.

“This is the worst day of our lives,” she said through tears.

Angcao said her parents had worked hard to help send her and one of her siblings to school.

Another worker, plumber John Carlo Villarente, said he had stepped outside the building about two hours before the collapse to get a drink. Then the structure came down.

“I was so shocked, there were people inside, including my nephew,” Villarente said. “We ran and tried to help, but we were not allowed to get near because people said it was very dangerous.”

Randy Alapide, a 41-year-old plumber who was off-duty at the time, rushed back to the disaster scene and helped rescuers by drawing a map showing where trapped workers may have been located.

“I know three of the missing,” he said. “They are breadwinners, and they have families waiting for them.”

Authorities said rescue efforts would continue into the night until everyone is accounted for.

Regional police director Brig. Gen. Jess Mendez said crews were not giving up as investigators began looking into what caused the building to collapse.

For now, the scene remains a desperate search through concrete, steel and silence, as families wait for the news they fear most.