A mine worker was killed in an underground accident at the National Coal Mining Museum near Wakefield.
The experienced 58-year-old, who has not been named, suffered fatal injuries after becoming trapped by heavy machinery he was working on deep underground at the museum at the former Caphouse Colliery, Overton.
Police and the Health and Safety Executive are investigating the incident, which happened just after 8am yesterday.
He was employed by a local mining company doing contract work at the museum.
Since last October, his firm has been working on a 2.7m Heritage Lottery funded project to extend an underground roadway to enhance the visitor experience at the museum, a registered charity.
It is the first time tragedy has struck at the museum, which opened in 1988 and is a popular tourist destination where visitors are invited to go 450ft down one of the oldest working mines in England.
A museum spokeswoman said the museum would be closed today as a mark of respect.
She said: "It is believed he was trapped by the machinery he was operating. The work was due to be completed in the next couple of weeks.
"The Health and Safety Executive's Mines Inspectorate, together with the local police,are carrying out a thorough investigation into the accident."
She added: "The museum is very saddened by this incident, and extends
its deepestsympathy to the family, friendsand work colleagues of the man."
The museum has won a string of awards and many of the100,000 visitors a year go underground, accompanied by retired former miners, on a tour ofold workings.
A West Yorkshire Police spokeswoman said: "A man was taken to Pinderfields with injuries from which he later died. The coroner's officer is aware and the Health and Safety Executive is aware and is dealing with it."
A Health and Safety Executive spokesman said: "We are aware of the incident and are investigating."
Last November the Government revealed it is ending its funding of the museum. The museum was left to seek a new sponsor after the Department for Culture, Media and Sport announced it will end the 2.8m contribution it makes to the museum's 3.2m budget after 2014/15.