The man had opened fire against the security forces, one of whom also died, the KGB security service said in a statement. It also said his wife had been arrested.
Reuters could not independently verify the statements or footage of the incident that was aired on Belarusian state television.
EPAM declined immediate comment. The U.S. embassy did not provide immediate comment.
Local media and a senior adviser to exiled opposition leader Sviatlana Tsikhanouskaya identified the man killed as Andrei Zeltser, an IT worker with EPAM.