A runaway iron-ore train careered 92km without its driver before being deliberately derailed yesterday morning, causing millions of dollars in damage and lost production.

The fully laden BHP train — almost 3km long with its four locomotives and 268 wagons — reached average speeds of about 110km/h on the track between Newman and Port Hedland.

The train was carrying ore from the Area C mine near Newman about 4.40am when the driver stopped about 210km from Port Hedland and got off to inspect one of the wagons.

The train then started to move with no one aboard.

BHP said it derailed the train from its remote operations centre about 50 minutes later by switching a set of points on the track.

The derailment happened about 120km from Port Hedland.

The Australian Transport Safety Bureau has begun an investigation into the incident.

Two investigators were sent to the Pilbara.

A BHP spokeswoman said no one was injured and the Pilbara miner had suspended all train operations.

“We are working with the appropriate authorities to investigate the situation,” she said.

BHP declined to give further details, including what might have caused the incident and how long operations will be halted.

The mining giant exported 69 million tonnes of iron ore from Port Hedland in the three months to September.

Despite suspending its train operations, it is likely BHP will be able to continue its mining and shipping operations for several days by adding to its iron ore stockpiles at the mines and depleting stockpiles at its export facility at Port Hedland.

Before rail operations can resume, the site of the derailment will need to be cleared of rolling stock and the track repaired.

While BHP’s Pilbara operations have had derailments in the past, none have been of this scale.

In 2015, a 25-wagon derailment shut down BHP’s railway operation for three days before traffic resumed.

According to a report released last month, the ATSB said the incident was caused by a broken rail, probably with a defect that could have been detected but was not. The report said that, as a result, BHP accelerated the re-railing of more than 800km of track and improved the detection of cracks in rails.

In February last year, about BHP 40 ore wagons came off the rails about 130km south of Port Hedland.

Rio Tinto, the other major Pilbara iron ore miner, has also had derailments.

In December 2015, 56 of its ore wagons derailed because of a small track misalignment.

The line was operational three days later.

In July this year, Rio delivered its first iron ore to port using a driverless train. BHP are yet to introduce the technology.