A worker has died after being struck by a locomotive at a BHP site in Western Australia's Pilbara region.

BHP WA iron ore asset president Brandon Craig said in a statement the man was fatally injured in an incident at the company's rail yard in Port Hedland at approximately 9:30pm on Tuesday.

WA Police responded to the incident and will prepare a report for the coroner.

The Office of National Rail Safety and WorkSafe have been informed.

Mr Craig said BHP was devastated by the tragic event.

"That is nothing compared to the grief and loss being felt by the person's family, friends and colleagues," he said.

The mining giant says its iron ore operations have been suspended for 24 hours.

WorkSafe Commissioner Darren Kavanagh said any work-related death was a tragedy and extended his condolences to the worker's family and colleagues.

In a statement, he said investigators would examine the circumstances of the incident, with a view to ensuring compliance and preventing similar incidents in future.

The Office of the National Rail Safety Regulator was also investigating the incident, Mr Kavanagh said.

Union to launch investigation

WA Mining and Energy Union state secretary Greg Busson also offered his condolences to the deceased man's family and work colleagues.

He said details were limited, but authorities and the union would start investigating the incident.

"We'll be looking at the evidence once it's collected," Mr Busson said.

"Whether you're an experienced operator or a new starter, it just goes to show you can't take your own health and safety for granted."

He urged witnesses and people who knew the deceased man to contact support services.

"Our concern at the moment is the health and safety and mental health of people on site that may have known the person and … anyone [who] actually witnessed the incident," Mr Busson said.

"If it takes an extra couple of minutes to do a job safely, please do so."

The worker's death is the first in WA's mining industry since October last year, when a horror stretch saw two onsite deaths within 72 hours.

A man was killed at the Hamlet gold mine near Kambalda on October 12 and another worker was killed at the Karlawinda gold mine, south east of Newman, two days later.

Opposition urges 'vigilance'

WA opposition leader Shane Love said his thoughts were with those who knew the man.

"I think any tragedy of this sort, we need to be mindful of the family and the workers, the co-workers of that person," he said.

"It just highlights, I think, the need for constant vigilance in workplace safety, especially in those high risk environments such as mining."

Mr Love said the incident was a reminder of how dangerous the resources industry can be.

"I'd just urge everyone to keep safe at work and keep your mind on the job," he said.

"I'm not saying anything happened here that was anybody's fault, but a death is always something which should be avoided."