Another freight train derailment in Hokkaido early Thursday disrupted commuter runs between Sapporo and Hakodate, Japan Freight Railway Co. said.

The driver found that one of his two locomotives had derailed between Toya and Usu stations on the JR Muroran Main Line around 4 a.m. after noticing an abnormal noise, according to Japan Freight.

Several wheels at the rear of the locomotive came off the tracks, according to Japan Freight and Hokkaido Railway Co. (JR Hokkaido), which owns the tracks.

The transport ministry's railway accident panel has sent three investigators to the scene.

The two locomotives were pulling 17 freight cars en route from Tokyo to Sapporo at the time. The train was going about 70 kph before the driver stopped. The driver was the only person in the train and was not injured in the incident.

The locomotive in question was built in 1997 and last underwent inspection at the end of December. The tracks in the area were last inspected in early December and showed no abnormalities, according to JR Hokkaido.

Both the inbound and outbound tracks on the Muroran Main Line have been closed, forcing over 40 services, including limited express services connecting Sapporo and Hakodate, to be cancelled.