ERLANGER, Ky. -- An explosion at a candy factory closed a road near the region's main airport Tuesday morning.
It's at least the third blast at Perfetti Van Melle USA since 2003. The company makes some well-known candy brands, including AirHeads and Mentos.
No one was injured in Tuesday's incident, Boone County officials said. Initial reports indicated there was a fire, but company spokeswoman Stephanie Creech later said there was only an explosion in one of the sugar manufacturing tools.
"You could see a slight plume go up, and you could smell the sugar -- sweet smell -- in the air," witness Amie Roberts said.
Point Pleasant Fire Chief Mike Giordano said the explosion was so loud that firefighters heard it at the fire station before emergency calls began to come in.
About 40 employees were at the plant at the time. Manufacturing was shut down for the shift.
Officials were working to determine the cause of the explosion. They were looking at the top of the roof connecting to the plant's sugar silo. Giordano said that built-in pressure relief points limited the extent of the damage.
"That process of moving a large amount of material through pipes creates static electricity, so that's a problem they're battling on a regular basis. I'm not saying that's what occurred here, but that's what we're continuing to concentrate our investigation on," Giordano said.
Turfway Road was closed at Donaldson because of Tuesday's emergency response. The factory is located just east of the Cincinnati-Northern Kentucky International Airport.
In December 2015, a silo exploded and caught fire at the plant. Officials said dust from candy-making operations likely caused the blast. The subsequent fire burned through panels to the side and back of the building, but no one was injured.
And in 2003, a static charge sparked an explosion and the roof caught fire. The blast blew off the back wall of the plant and injured one worker, but he survived. The factory reopened the next day. The Occupational Health and Safety Administration found no violations during a safety investigation conducted the same month.
OSHA did find violations at the plant on two occasions, though none was recent. In 2006, there were four health-related violations, and in 2001, there were two. Like the 2003 safety investigation, a health-related investigation in 2007 turned up no violations.
OSHA is not investigating Tuesday's explosion, a representative said. After the 2015 fire, company president Mehmet Yuksek pledged a further review.
“As violently as it shook this place, for it not to harm anybody or anything -- for anybody not to be injured, it's a shocker," Roberts said.