Authorities found what appears to be human remains on the driver's seat of a truck that fell into a sinkhole after a road collapsed in late January in Yashio, Saitama Prefecture, NHK reported Thursday.

Saitama Gov. Motohiro Ono gave the news to reporters on Thursday after police and firefighters started that morning to inspect the inside of a sewage pipe at the site for the first time in hopes of finding the 74-year-old driver of a truck that fell into the sinkhole, the report said.

At around 4:40 a.m. Thursday, a bus carrying about 20 police officers, firefighters and others arrived at the site, which smelled of sulfur. Wearing double protective suits with oxygen cylinders and masks, they headed for the pipe about 10 meters below the surface.

According to prefectural government and other officials, the inspection was conducted early in the morning because the time period sees a relatively small amount of sewage. Three teams were mobilized for the inspection, and two of them worked for about 20 minutes each.

In the incident, which occurred at around 9:50 a.m. on Jan. 28, the central part of an intersection collapsed and a passing truck plunged into the sinkhole. The truck's bed has been recovered, but the cab remains inside the pipe.

Since a drone survey confirmed a shape resembling a person inside the cab in February, the prefectural government has been conducting drilling work to reach the driver's seat while installing a makeshift pipe to divert sewage.

The construction of the bypass pipe was completed on April 24. Ono had said at the time that the prefecture will begin the inspection inside the sewage pipe where the truck cab remains as soon as possible.