Because the movie's second unit team were running behind schedule, it was decided that dummy cartridges (cartridges that outwardly appear to be functional, but contain no gunpowder) would be made from real cartridges. A cartridge with only a primer and a bullet was fired in the pistol prior to the scene. It caused a squib load, in which the primer provided enough force to push the bullet out of the cartridge and into the barrel of the revolver, where it became stuck.
The malfunction went unnoticed by the crew, and the same gun was used again later to shoot the death scene, having been re-loaded with blanks. Nevertheless, the squib load was still lodged in the barrel, and was propelled by the blank cartridge's explosion out of the barrel and into Lee's body. Although the bullet was traveling much more slowly than a normally fired bullet would be, the bullet's large size and the extremely short firing distance made it powerful enough to fatally wound Lee.
When the blank was fired, the bullet shot out and hit Lee in the abdomen and lodged in his spine. He fell down instantly and the director shouted "Cut!", but Lee did not respond. The cast and crew filming rushed to him and noticed he was wounded. He was immediately rushed to the hospital, Lee’s heart had stopped once on the set and once in the ambulance on the way. Following a six hour operation to remove the bullet and despite being given 60 pints of blood, it was too late. The damage the bullet caused was too great. He was pronounced dead at 1:03pm.
