What appeared to be human bones have been found in a molten iron pot that operates at temperatures over 1,000 degrees Celsius at a Nippon Steel factory in the city of Oita, the steelmaker said Wednesday.

The Oita police said it’s highly possible that the bones belong to a male employee who had been reported missing on Tuesday, and are currently conducting DNA tests to identify the remains.

The 30-year-old employee had been reported missing since around 7 a.m. Tuesday. The Oita police said they searched the factory and found remains of what appeared to be human bones in the pot four hours later.

The missing employee, who oversaw the iron melting process, started his shift from 7 p.m. on Monday. The melting pot, which has a diameter of about 5 meters and a depth of about 4 meters, was located 5 meters below where the man had been working.

Eijiro Kawano, spokesperson for Oita Chuo Police Station, said investigations are ongoing on the whereabouts of the missing employee and whether the discovered remains are human bones or not. If they are, they will work to identify the remains, and investigate how they got into the melting pot, he said.

The steelmaker’s Oita factory manufactures steel for ships, industrial machinery, construction materials and bridges, and exports its products mainly to Southeast Asia, the Middle East and China.

Nippon Steel said it would fully cooperate with investigators.