Jenifer Lowe / AP This photo provided by the Marion County Sheriff's Office, a Marion County Crime Scene investigator photographs the damages caused by an explosion at an equine rehabilitation center in north Florida's horse country that killed a worker and a horse in Ocala, Friday, Feb. 10, 2012.

An explosion that killed a 28-year-old woman operating a hyperbaric chamber at a Florida equine therapy center was sparked by a horse kicking the side of the chamber with its metal shoes, authorities ruled.

Erica Marshall, an employee at Kesmarc Equine Rehabilitation facility in Marion County, died when the chamber she was running exploded on Feb. 10. Sorcha Moneley, 33, a visiting observer from Ireland, was wounded in the blast.

The sheriff's report said the horse, which also died, was wearing steel horseshoes inside the oxygen-rich chamber. Moneley told fire rescuers the horse kicked the inside walls, removing an inside protective layer and causing sparks before the explosion.



According to the sheriff's report, witnesses were at odds as to whether the horse had been sedated before entering the chamber, a precaution to lessen the chances of the animal kicking and causing damage.

Authorities at the scene said the end of the barn where the chamber had been housed was completely destroyed in the blast. Marshall's body was found buried in the rubble of the control room.

Facility manager Leonora Byrne told investigators horses are sent to the hyperbaric chamber for post-surgery rehabilitation, treatment for soft tissue damage or rest and relaxation.

Byrne also said Marshall had been trained to run the chamber and had been controlling it for about two years.

The horse that was in the chamber at the time of the explosion had been in it about four times before, Byrne told officials. She said some horses are given a mild sedative before being put in the chamber, but this particular horse had not been medicated.

Shoes not taped

However, Moneley told an investigator the horse had been given a sedative before being led into the chamber. She explained the horse's feet were fit with steel shoes that had not been taped or covered before he was brought for treatment, but said that was unnecessary since the inside of the chamber was lined with a protective coating.

Moneley said the horse had been in the chamber for about 20 minutes and had become unsettled. When it started kicking, a lid at the back of the chamber was dislodged and fell, revealing raw metal. The horse continued kicking, causing sparks. Moneley said she and Marshall noticed bigger sparks, then flames inside the chamber.

She said she left the area to call the fire department as Marshall prepared to bring the chamber to normal pressure, and that Marshall was "staring at the monitor and crying," according to the report.

Moneley then said she heard an initial blast and a second, larger explosion, which knocked her down and felt as though "hot gas had surrounded her," according to the report. A sheriff's office spokesperson told msnbc.com Moneley was tossed a considerable distance by the explosion. She suffered a head injury and was taken to a hospital in Gainesville.





Marshall's funeral took place Thursday.

