UPDATE: 8:05 p.m. EDT — Police said a gunman burst into the Thomas and Betts electronics plant in Athens, Tennessee, Thursday and opened fire, killing two people before shooting himself to death.

Earlier reports indicated the gunman had shot three victims.

Police Chief Chuck Ziegler told reporters people were fleeing the building when police arrived. He said the gunman was an employee of the factory.

WATE-TV, Knoxville, reported police have yet to release the identities of the shooter or the victims.

Original story

A lone gunman burst into an Athens, Tennessee, factory and opened fire Thursday, killing three people before he was shot to death, police said.

Police said the gunman went directly to the production manager’s office at the Thomas and Betts factory shortly after 4 p.m. and killed his first victim, the Daily Post-Athenian reported. He then shot and killed two more people in the main part of the plant. Employees ran from the building, taking shelter in a nearby wooded area, a cemetery and another plant.

It was not immediately clear whether the gunman killed himself or was killed by police. The scene was declared secure shortly after 5 p.m.

A nearby high school was placed on lockdown during the incident.

Police scheduled a 7 p.m. news conference.

The plant makes connectors and components for the electrical and communications industries.

The Bureau of Labor Statistics reports an average 551 people were killed in workplace homicides from 2006 to 2010, the last year for which statistics have been compiled. Shootings accounted for 78 percent of the 518 workplace homicides in 2010. Eighty-three percent of the incidents were in the private sector and 80 percent of victims were men.

The deadliest workplace homicide in the United States occurred in Edmond, Oklahoma, in 1986. Patrick Henry Sherrill, 44, killed 14 co-workers at the Edmond post office before committing suicide. Some reports described him as erratic and irritable while others say he was the victim of management bullying.

Before Thursday, the most-recent workplace multiple homicide occurred Feb. 25 at lawnmower-maker Excel Industries in Hesston, Kansas. Cedric Larry Ford, who was killed by police, shot at two vehicles and then fired at on-coming traffic before entering the factory. Among the three people killed by Ford was the first police officer responding to the scene, Chief Doug Schroeder.