A former employee walked into a conveyor belt factory and opened fire before officers confined him to a small storage area, prompting a seven-hour standoff that ended with the man's surrender, authorities said.

One person suffered minor injuries in the shooting that began about 3 p.m. Thursday at Beltservice Corp., police spokesman Mason Keller said. At one point, the gunman reloaded his shotgun in a parking lot before re-entering the building, he said.

Officers confined the gunman to a storage area, where he negotiated with police by telephone for several hours.

"A little after 10 p.m., the guy put down the gun and came out to police," Keller said. The suspect's name was not released.

Company co-founder and chairman Dick Engelsmann said 110 employees were in the building at the time of the shooting, and all were evacuated.

The wounded employee, 61-year-old Jake Lewman, was struck in the leg. He was treated and released from a hospital.

One plant worker said he knew the shooter and that the man was having personal problems and missing too many days at work when he was fired about a year ago.

"He told me if he lost his job he wouldn't be able to support his family," Marcus Jordan said.

Craig Kopplin said he had just begun his shift when he heard a gunshot. "Boom! Then instantaneously, I heard another," he said.

Another worker, Kevin Tippit, said he heard at least five gunshots. He bolted and sought shelter in a neighboring building's dock area.

"I was looking through the windows, and the guy came out, reloaded his gun and went right back in," he said. "It's craziness, craziness."

The Beltservice factory is in an industrialized area west of St. Louis, near the training facility of the St. Louis Rams football team.