Health and safety officials in California have launched an investigation after a crew member died on the set of Johnny Depp's new movie The Lone Ranger.

Welder/water safety expert Mike Bridger died on Friday (21Sep12) after reportedly suffering a heart attack while working inside a large liquid tank.

Officials from the Division of Occupational Safety and Health - California Department (Cal/Osha) have now started a probe into the incident and they will be looking at the equipment used on set as well as the water tank itself, according to

Health and safety officers will also conduct interviews with all cast and crewmembers who were on the set at the time of the tragedy.

Bosses at Disney, the studio behind the film, have vowed to fully support an official investigation.

The final report into Bridger's death will take up to six months to complete.

The movie, starring Johnny Depp and Armie Hammer, is due for release next year (13).