Saline County Sheriff Alan Moore told the Lincoln Star Journal that about 35 people were at the Americold Logistics facility when the gunman opened fire at about 10 p.m. Wednesday. The gunman, whose identity hasn't been publicly released, worked at the plant, Moore said.
Moore said about 50 officers responded to reports of the shooting, unsure of whether the shooter was still a threat.
"When we first came across him, it appeared that it was a self-inflicted wound that ended it," the sheriff said, referring to the gunman.
Two of the wounded were taken to a Lincoln hospital. The other was treated at the Crete Area Medical Center, in Crete. Their names and conditions weren't available. It was unclear whether they also worked for Americold.
The sheriff didn't immediately return a call Thursday morning from The Associated Press.
Authorities locked down the facility after the shooting but allowed workers to leave early Thursday.
Spent shells were found outside the building, inside in a cafeteria and other areas, Moore said.
Americold also has facilities in Fremont and Grand Island, Neb. The company's website describes it as the largest temperature-controlled food storage network in the U.S., with about 100 facilities nationwide.