A longtime employee at a St. Louis power company opened fire upon arriving to work Thursday morning, fatally wounding three people before apparently killing himself.
The gunman was identified by fire officials as Timothy Hendron, 51, an active employee at ABB power plant in the north side of St. Louis. Police wouldn't confirm the gunman's identity but said he is believe to be among the dead.
"We are very confident that this is the shooter," Police Chief Dan Isom said at a news conference.
Eight people were injured by the gunman. Five of them have been hospitalized, three of whom are in critical condition, police said. Police have not publicly identified any of the victims because they said they are in the process of notifying their families.
Hendron reportedly arrived at work at about 6:30 a.m. with a large assault rifle and handgun. Police said the incident began in the parking lot and soon moved into a nearby building.
It wasn't clear how many shots were fired, but authorities said employees scurried to find refuge from the bullets on the roof and in closets.
Police said they still have tactical teams inside the 200,000 square foot building. They don't believe there are other victims.
Dotson said it is unclear what motive the suspect may have had.
In 2006, Hendron and other ABB workers reportedly sued the company over retirement losses. The federal lawsuit accused ABB and its pension-review committee of causing their 401(k) accounts to include investment options with "unreasonable and excessive" — and undisclosed — fees and expenses. The suit went to trial Tuesday in Kansas City.
Earlier in the day, police had set up a two-mile perimeter around the area and closed Interstate 70 between Kingshighway and Goodfellow in both directions near the shooting scene. SWAT team members searched the area for hours, unsure if the gunman was still inside the building.
A spokesman for the Swiss-based ABB told Fox News that the power company was working with authorities on both sides of the Atlantic.
"We are shocked about the event and our thoughts are currently with the families," Thomas Schmidt said.
The suspect's friend and neighbor, Ronald D. Bartram, told the St. Louis Post-Dispatch that he could not believe that his friend would do such a thing and is worried that police are looking for the wrong man.
Bartram said that Hendron has worked for the company for a long time and that he spoke to Hendron just two days ago and nothing was bothering him. He told the paper that Hendron is a hunter and owns guns.
"I am very upset," Bartram told the paper. "He's a good friend of mine and I am really concerned. He is a good man."
Several employees in the building ran to the building's rooftop to get away from the gunfire, the St. Louis Post-Dispatch reported. The paper also reported that one worker had locked himself inside of a maintenance room in the building.
ABB Group makes power transmission and industrial automation equipment. The company manufactures transformers at the St. Louis site, according to its Web site. A spokesman says about 270 people work at the St. Louis plant.
ABB has operations in roughly 100 countries, employing about 120,000 people. Last October, ABB reported third-quarter earnings of more than $1 billion.
The Associated Press contributed to this article.