A tragic accident struck northwest China on Friday when a section of a bridge under construction collapsed, killing at least six people and leaving 10 others missing.

The incident occurred on the Sichuan-Qinghai Railway, where workers were building what was set to be the world’s largest-span double-track continuous steel truss arch bridge. The bridge is also notable for being China’s first railway steel truss arch bridge crossing the Yellow River, the country’s second-longest waterway.

Footage shared by state broadcaster CCTV showed the middle arch of the bridge suddenly giving way, crashing into the river below. Rescue operations are ongoing.

According to Xinhua News Agency, a steel cable failure is believed to have triggered the collapse. At the time of the accident, 15 workers and a project manager were on-site.

Photos released by state media reveal the devastation — a massive gap in the bridge’s midsection, flanked by towering scaffolds and cranes that now stand idle.

This disaster highlights the risks tied to China’s ambitious infrastructure projects, even as the country continues to push for record-breaking engineering achievements. For now, families of the victims wait anxiously for news of the missing, as investigators work to determine exactly what went wrong.