Two workers have been trapped under rubble after a building that was being demolished collapsed on Saturday, rescuers said.

The motel in central Seoul collapsed at around 11:30 a.m. while the workers were dismantling it, they said.

A rescue operation is underway for the two who are known to be trapped underground, according to the rescuers.

"The two were sprinkling water on the construction site to avoid raising dust," a firefighter said.

Two other workers sustained minor injures and were taken to a nearby hospital, rescuers added.

The demolition, which began in October, was to be completed next month with the plan to build a new tourist hotel on the site.

Temporary traffic controls are in operation near the site of the accident, police said.

Authorities added that they will investigate the exact cause of the accident and whether the workers had adequate safety measures. (Yonhap)