Water and debris continue to hamper the search for a truck driver now trapped for a week in a massive sinkhole that suddenly occurred in a city north of Tokyo.

The cave-in happened at an intersection in Yashio City, Saitama Prefecture on January 28, swallowing the truck. The condition of the 74-year-old driver remains unknown.

The sinkhole is about 15 meters deep. Heavy concrete structures and other debris are piled up inside. Water, believed to be sewage, is also spewing out.

Rescue workers have been unable to launch a full-scale search for the driver due to safety reasons.

Work began on Monday to dig a second slope to the cavity to enable heavy machinery to clear away soil and debris.

Prefectural officials have also asked households and businesses in 12 cities and towns nearby to stop using water for three hours from 2 p.m. Tuesday, except when absolutely necessary.

Officials say they want to check whether the stoppage would change the water level inside the sinkhole. They hope to conduct a full operation to look for the driver.