OSHA, JEA, JSO and more are working to find the cause of an explosion that severely burned two men. 

JEA spokeswoman Gerri Boyce said the two men were rushed to the hospital with severe burns caused by an arc flash in the electrical equipment that powers the office building, primarily occupied by CSX Corp.  One man worked for JEA; the other worked for Graham. 

We asked William Burkhardt, a 35 year construction industry veteran and instructor with the North East Florida Safety Council, for insight into the accident.  Burkhardt said two lines likely became crossed inside the unit, and the flash occurred when the men opened the door.  Burkhardt said despite required training by OSHA arc flashes send at least one electrician to the hospital every day in the U.S.  He said they are impossible to predict, and the heat can exceed 30,000 degrees, which is three times hotter than the sun.

Both victims were transported to UF Health, where one man's injuries are now listed as serious.  the other was flown to the Shands Gainesville burn unity with life-threatening injuries.