St. Louis, Missouri (CNN) -- An employee at a transformer manufacturing company opened fire on his co-workers Thursday, killing three people before turning the gun on himself, police said.

Five other ABB Inc. employees were wounded in the shooting in the company's factory in St. Louis, police said.

A law enforcement official identified the suspect as Timothy Hendron.

Hendron is among a group of ABB employees listed in a lawsuit filed in 2006 against administrators of the company's retirement plan. The suit, filed in federal court, accuses the administrators of, among other things, causing the plan to include "unreasonable and excessive" fees and expenses, paid by participants, without their knowledge and not used for their benefit or that of the plan.

Linda Siegfried, a spokesman for the law firm representing the plaintiffs, confirmed to CNN that Hendron was among the plaintiffs, although his name is spelled three different ways in court documents.

A trial on the matter is taking place in Kansas City, Missouri, Siegfried said. She didn't know whether Hendron would have been required to be present. Online federal court records show the trial began Tuesday.

Siegfried would not comment further except to say the firm offers its concern for the welfare of the victims.

The shooting occurred just before 6:30 a.m. Arriving officers were told that a man had entered the building with a rifle and a handgun, and that several people had been shot, police said.

"Police made a perimeter around the business and located those victims who needed medical attention," a St. Louis Metropolitan Police statement said.

Of the five at area hospitals, three victims were in critical condition and two in fair condition, police said.

KSDK: Four dead, five wounded at ABB Power

Authorities conducted a room-to-room search of the large building, as well as surrounding buildings at the ABB complex, the statement said. Interstate 70 and surface streets in the area were initially shut down.

ABB spokesman Bob Fesmire said earlier that about 100 employees work at the facility, but some of them were unable to come in Thursday because of heavy snow.

CNN's Kara Devlin, Ashley Hayes and Carol Cratty contributed to this report.