A second person died on Friday as a result of an explosion that rocked the Williams Olefins petrochemical plant in Geismar, Louisiana, and injured more than 100 workers a day earlier.
Scott Thrower, 47, died as a result of injuries he suffered in the explosion, Louisiana State Police said.
Zachary Green, 29, a plant operator who had worked at the facility since October, died on Thursday shortly after being hospitalized following the incident.
Five people remained hospitalized in conditions ranging from critical to fair on Friday.
The blast sent a huge fireball and column of smoke into the air above the plant along the Mississippi River, about 60 miles (100 km) from New Orleans.
Williams Olefins CEO and President Alan Armstrong called the explosion "a tremendous tragedy."
"A lot of us in this industry have spent much of our careers working to make it safe, so when something like this happens, honestly, it feels like a big failure," Armstrong told a news conference, his voice shaking, shortly before police announced a second person had died.
"Your heart sinks, and it's just hard to know what to do, you feel pretty helpless," Armstrong said.
Parent group the Williams Companies Inc operates the plant and holds an 83-percent stake in it.
The company had yet to identify the cause of the explosion and will launch an investigation as soon as all the remaining flammable hydrocarbons in the plant dissipated and it was safe to re-enter, plant manager Larry Bayer said.
Louisiana Governor Bobby Jindal on Thursday vowed to hold responsible whoever may be at fault.
The company's injury toll of 100 was higher than the figure of 73 given by Jindal on Thursday.
Bayer said 839 people were at work in the plant at the time of the explosion, a larger-than-normal number because a major expansion was under way.
A small number of employees were working in 12-hour shifts "to assure the plant is being safely shut down and monitored," Bayer said, declining to speculate when the plant would reopen because the extent of the damage was still unknown.
The materials that burned in the fire after the explosion were primarily propane and propylene, Bayer said.
"We anticipate we will have everything burned off in a day or so," Bayer said.
Three of the injured remained in a burn-care unit at Baton Rouge General Medical Center, listed in critical to fair condition, and two others were at Our Lady of the Lake Regional Medical Center, listed in critical and fair condition, respectively, according to information from the hospitals.
Louisiana State Police concluded operations at the site and relinquished control of the plant back to Williams Olefins, police said in a statement.
The state Department of Environmental Quality would continue to assess air and water quality in the area and U.S. Occupational Safety and Health Administration personnel would begin an "in-depth investigation as to the exact cause of the fire," police said.