The single blast at Ocracoke, N.C., came as workers were unloading fireworks Saturday from a truck at the Anchorage Marina, shaking homes and businesses across the southern end of the island and rattling residents and tourists. One of the workers died at the scene Saturday and three others died later at area hospitals, including one who died on Sunday, Hyde County spokeswoman Jamie Tunnell said.
Hyde County manager Carl Klassen said he could not yet release the names of those killed and did not have an update on the condition of a person injured.
Agents with the Bureau of Alcohol, Tobacco, Firearms and Explosives, determined the cause was accidental, said spokesman Earl Woodham.
North Carolina does not require licensing or certification for people who handle fireworks, said state fire marshal spokeswoman Johannna Royo.
That's not unusual, said John Steinberg of Randallstown, Md., spokesman and co-director of training for Pyrotechnics Guild International, which provides training for fireworks operators. In most cases, the companies provide training because their insurers require it, he said.
The driver would be required to have a commercial license with a hazardous waste endorsement from the federal Transportation Department, Steinberg said.
"I don't think that states adopting unique licensing procedures does anything more than reassure those who think you ought to do something that you've done something," he said.
The state Labor Department will look at the company's training records to make sure it trained employees "to ensure a safe and healthful workplace," said agency spokeswoman Dolores Quesenberry.
The Ocracoke victims worked for Melrose South Pyrotechnics near Rock Hill, S.C. The company said it sent a representative to work with investigators.
The company holds wholesale and storage licenses from the South Carolina Board of Pyrotechnics, and has year-round permits to conduct fireworks displays, said Jim Knight, spokesman for the state Department of Labor, Licensing and Regulation.
"Everyone at Melrose South Pyrotechnics is grief stricken over the loss of life and injuries sustained in this terrible tragedy," the statement said. "These types of incidents are difficult to determine what really happened until all aspects of the investigation are complete."
Asked about previous accidents, a woman who answered the phone Monday at Melrose said officials were making no comments beyond its three-paragraph statement.
A July 2001 explosion at Melrose's Catawba plant killed a 24-year-old seasonal employee and injured two workers.
In a settlement with the state, the company agreed to pay a reduced fine of $20,750 "for economic reasons only," - less than half of the initial fine of $47,250 - without acknowledging any wrongdoing, and agreed to allow unannounced plant inspections without a warrant for three years.
The report cited the company for nine serious violations, which means death or serious physical harm is likely to result from a hazard the company either knew about or should have known. Those included insufficient ventilation, explosives being unpacked within 10 feet of a storage container, the container's door being open when it should have been closed, lack of training on the safe handling of returned fireworks, and a driver transporting fireworks without the required hazardous materials license.
Two years later, a follow-up investigation resulted in a $510 penalty - reduced from $1,275 - for not having a hood guard on a circular hand-fed ripsaw, a serious violation, according to Occupational Safety and Health Administration records.
On Independence Day 2007, two Melrose South Pyrotechnics employees were hurt during a fireworks show at Fort Stewart, Ga. Officials blamed a malfunctioning firework that detonated prematurely and started a chain reaction.
A decade earlier, two Melrose workers were injured off Hilton Head Island after embers landed on a case of undetonated fireworks and set off an explosive chain reaction of fireworks on a floating barge.