An explosion at an Illinois ammunition factory killed one employee, authorities said.

The explosion Thursday afternoon killed Oscar "Zeke" R. Bettorf, 60, of Bunker Hill, Madison County Coroner Steve Nonn said.

Bettorf was the driver of a semitrailer loaded with shotgun shell primers that exploded while being transported inside the Winchester ammunition plant owned by Olin Corp., Nonn said Friday.

ILLINOIS AMMUNITION FACTORY EXPLOSION KILLS 1 EMPLOYEE

"We were driving through there and heard a big boom, pushed the van a little bit," said Dustin Courtouise, who lives in East Alton.

The factory is about 20 miles north of St. Louis on the Illinois side of the Mississippi River.

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"There was a loud explosion heard throughout the town," East Alton Mayor Darren Carlton said.

Winchester said it would fully investigate the "tragedy."

"Our thoughts and prayers are with our employee’s family and coworkers," the company said in a statement.

Winchester’s manufacturing operations are located in East Alton and Oxford, Mississippi. It makes ammunition for various markets, including the U.S. military.