COLUMBUS, Wis. (AP) -- A fire continued to burn Tuesday at a chemical company that had previously been cited for unsafe handling of chemicals and hazardous materials.
A fire broke out at a warehouse at Columbus Chemical Industries about 8 p.m. Monday, and a series of three explosions rocked the building just after firefighters arrived, Columbus Acting Fire Chief Mark Kenevan said.
Firefighters withdrew to let the chemicals burn and the fire extinguish itself. Dozens of neighbors were evacuated. There was still one hot spot Tuesday morning, said Steve Quandt, the company's executive vice president.
But emergency officials said they hoped to sound an all-clear by noon, reopen roads and let nearby residents return home.
Officials have been monitoring contaminants in the air, but so far have found nothing that exceeded federal air standards, Quandt said.
"We have zero reports of any negative health impacts to citizens," he said.
But Jim Neuman, 43, who lives about half a block from the plant, told The Associated Press the air smelled like sulfur and he, his girlfriend and her son woke up with sore throats Tuesday morning after they were evacuated. He wasn't sure whether they would seek medical attention.
"We got a blast of something," Neuman said.
The warehouse was burning when firefighters arrived Monday, Kenevan said. They were still outside when two large explosions hit 30 seconds apart, followed by a smaller one about a minute later. Three firefighters knocked to the ground were taken to a hospital, where they were treated for injuries and released.
"I was standing about 100 yards from the scene, and I felt the pressure quite well on my face and body," Kenevan said.
By Tuesday morning, 19 other firefighters and emergency workers also had been taken to a hospital for decontamination. Dodge County Sheriff Todd Nehls said that was standard procedure in situations involving hazardous chemicals.
Columbus Chemical Industries provides chemicals to high-tech and pharmaceutical companies, among others, according to its Web site.
Quandt apologized to the community after dozens of neighbors were evacuated Monday night.
"I would like to apologize to all the people we inconvenienced," he said at a Tuesday morning news conference.
No workers were at the plant, and it's not clear yet how the fire started, Quandt said. Company officials are eager to get onto the site after the fire is out and find out what happened, he said.
Firefighters made the right call to let the building burn and spare more injuries, Quandt said.
"As an employee, it's hard to watch your building burn, but it was the right thing to do," he said.
The company was fined about $4,300 in 2005 for 10 safety violations, including eight labeled "serious," according to the Occupational Safety & Health Administration. The violations involved handling of flammable and hazardous materials and maintenance of safety equipment.
OSHA spokesman Scott Allen says the company promptly corrected each violation and has had no problems since.
Columbus, a city of about 5,000, lies about 25 miles northeast of Madison. Tuesday morning, roads leading to the plant were closed, including state Highway 73 and U.S. Highway 151, the main road from the state capital. The sheriff's department advised drivers to avoid the area.
Residents within a half-mile radius of the plant remained evacuated Tuesday, Nehls said. Emergency officials set up a shelter, but most people stayed at a Super 8 motel in Columbus. Quandt said the company would pick up their tabs.
Dodge County authorities used an emergency notification system to call other residents in Columbus and nearby Beaver Dam and tell them to stay inside and keep their windows closed because of smoke.
Neuman's girlfriend, 44-year-old Kim Buss, said the explosion shook their house.
"It was just a ball of smoke," she said. "When it exploded, it was like a black mushroom. Looked like fireworks. Then we saw all the fire trucks leave (the plant)."
Neuman, Buss, her 11-year-old son, Cody, and their two dogs, Maggie and Blaze, and spent the night at the Super 8.
"We just took what we had on and went," Buss said.
Kelly Holder, 47, who lives about a half-mile from the plant, said she didn't hear an explosion, but she and her husband were watching television about 8 p.m. when she noticed fire trucks streaming into the neighborhood. She was standing outside about an hour and a half later when emergency officials walked up and told her to evacuate.
"We just got the bare necessities" and went to her sister's home a few blocks away, Holder said. About midnight, they were told to evacuate again. The family spent the rest of the night in a hotel in Columbus.
Associated Press Writers Dinesh Ramde and James Carlson in Milwaukee contributed to this report.