"The shooting took place in a building of the Aircraft Industries company before noon (1100 GMT)," police spokesman Ales Mergental told AFP.
Czech media said the gunman was 56-year-old Karel Musela, who blamed the managers for masterminding a shooting attack that left his brother, influential arms dealer and former Aircraft Industries board member Pavel Musela, paralysed in 2008.
"We have information suggesting he`s the gunman," the top-selling broadsheet daily DNES quoted a police source as saying.
The gunman also caused a light head injury to Aircraft Industries chief executive Ilona Plskova, DNES said on its website.
"There are three dead and one of the dead men is the gunman," regional police spokeswoman Jana Bartikova told AFP, adding the gunman had committed suicide.
"I won`t identify anyone as far as the dead and injured people are concerned. I`d be glad if their families learned about it from sources other than media," she added.
DNES said Musela, who had entrenched himself in the company headquarters, shot himself as the police surrounded the building.
A hundred police officers were in action, and the factory employees were evacuated, with some treated for shock.
"We went out to have lunch and when we got back, they told us not to go close to the windows," DNES quoted an employee as saying.
"We first thought it was a fire alarm, but then we heard it was for real," he added.
Aircraft Industries, majority-owned by Russia`s Ural Mining and Metallurgical Company, produces the L-410 turboprop transport plane in Kunovice, about 260 kilometres (160 miles) southeast of Prague.
The company with more than 650 employees raised profits to 173.6 million koruna (6.8 million euros, $9.3 million) in 2010, up from 125.6 million koruna in 2009, while its revenue rose by half to 1.17 billion koruna.
Aircraft Industries, former Letecke zavody Kunovice (LET), was declared "Company of the Year" in the region this year.
AFP/C003
Editor: Jafar M Sidik
Copyright © ANTARA 2011
