The Michigan fireworks factory where an explosion Monday killed five people was guilty of "serious and willful safety violations" according to state officials who investigated an earlier blast at the plant that left seven workers dead. A forthcoming Michigan Occupational Safety and Health Administration (MIOSHA) report on the December 11, 1998 explosion cited Independence Professional Fireworks Co. for violations that posed a substantial probability of death or serious physical harm to workers.

However, neither MIOSHA nor the federal Bureau of Alcohol, Tobacco and Firearms (BATF), which regulates fireworks manufacturers, ordered the factory closed. Independence is among the country's largest makers of display fireworks shells.

Another explosion Monday morning at 8:30 a.m. ripped through the plant near Osseo, Michigan, a small town in rural Hillsdale County, some 100 miles southwest of Detroit. Flames shot through a small shack where workers were assembling fireworks, only 100 yards from a structure that was destroyed in a massive explosion last December. Pittsford Fire Chief Craig Winner said it appeared that a firework had detonated on Monday.

The bodies of two men and two women were found inside the building. Company owner Robert Slayton was found alive outside, but died in the hospital later from critical burns. Victims were burned so badly that inspectors were using dental records to establish their identification. According to family, coworkers and friends, those who were killed were Leah Dunning, 34, a mother of three; Rick Wiggins, 30; Scott Burton; and the company owner and his wife Patricia Slayton.

The blast shocked and angered the community of 1,387 people, who were still collecting donations for a monument to honor the seven workers killed on December 11, 1998. Six women and one man were killed and another 13 were injured. The two explosions in little more than three months have killed half of the company's work force.

The lack of opportunities in the farming community apparently induced some of the workers to return despite the first explosion. Tammy Sykes said her neighbor Leah Dunning had been concerned about going back. "She wasn't crazy about going to back to work after the explosion in December. But it was a good paying job for around here," Sykes said.

Walter Adams, a former employee, told the Detroit Free Press about the hazardous nitrates, sulfurs, charcoal and black powder which the workers handled each day. Adams said, "We would roll the mixtures together, dry them and then wrap them." Inside the building "there were raw powders and such. They don't explode that much, but they burn real hot and real fast. I'd have to say that this happened because the stuff is so volatile. Even static electricity can set it off," Adams said. "We had some solutions that we had to mix by hand, using our fingers and going very slowly since even the friction could cause it to ignite."

Local residents who had sought to keep the factory closed after the first blast were outraged when the company resumed operations about a week ago. "We were so angry when we heard them testing fireworks. We didn't think they'd let them reopen. We didn't want them to," Paula Watters, who lives a quarter mile from the fireworks site, told the Toledo Blade. Ms. Watters' cousin, Joyce Carr, died in last December's blast. "Now we're reliving it all over again. Every time a car backfires we go crazy," she said.

Ms. Watters said she called 911 and the BATF to complain and urged her neighbors to do the same. But local officials said they were powerless because federal firearms and explosive regulations governed the plant's operations. The BATF, the state police fire marshal's office and the Hillsdale County sheriff's office, which for the most part have not finished their investigation of December's explosion, claimed they were not aware that the company was operating.

Mark Hady, BATF resident agent in charge, said the factory's license had not been revoked after the December explosion but refused to explain why. Detective Sgt. Ken Hersha of the State Police fire marshal division said the company kept its license because investigators could find nothing that contributed to the December blast's origin.

Kalmin Smith, the deputy director of the state's Consumer and Industry Services Department, a MIOSHA agency, said the state can only shut a company down if it finds clear and convincing evidence of an imminent threat of danger or death to employees. Even if MIOSHA had found several safety violations, he said, these may not have been the cause of either one of the explosions. "They don't have to report to us what they're doing," he added. "I assume they were operating normally until today."

Even before the December 1998 blast the company had a long record of accidents and safety violations. Disaster was narrowly averted in August 1983 when employees fled a building before an explosion at the plant, then located in Exeter Township in Monroe County. Township officials and residents complained to the BATF, and the company, then owned by William Richardson, moved to Hillsdale County the next year. Richardson, now listed as a consultant to the company, then sold Independence to Richard Slayton.

Safety inspectors issued 10 violation notices to the company in 1985 and 1986. In November 1991 another 19 citations were issued, including 9 for serious violations, but the company was only fined $1,200. Some of the violations included an open flame in a furnace in a building with fireworks, employees wearing clothing that could allow sparks to ignite and the lack of eye protection for workers.

According to inspection records, the company's owners fought many of the violations, appealing some for many years before complying. In September 1994 an inspector said Richardson angrily confronted her over a violation. In a report she said, "He became very agitated and said that ATF was the most despised agency in the federal government because of Waco and petty violations such as the one issued to Independence."

Safety inspectors have not been inside the plant since 1994 despite its unsafe record. The December 1998 explosion was the worst fatal accident in Michigan history. The second worst was the February 1 explosion at the Ford Rouge complex in Dearborn, which claimed the lives of six workers.

Over the last two decades successive administrations in state government, both Democratic and Republican, have cut funding for safety inspections. Between 1980 and 1998 the number of safety inspections carried out by the Michigan Occupational and Safety Administration fell by 73 percent, from 21,046 to 5,778. MIOSHA has only 42 inspectors to cover 216,000 workplaces in the state. Last year 1,273 industrial locations out of 16,800 were inspected.