By Agence France-Presse
The Czech CTK news agency said it was thought that the foreign victims could be Thai nationals.
The four-seater Robinson R44-Raven helicopter came down in an industrial zone in a suburb of the town of Plzen.
"Among the victims, there are three foreigners, two men and a women," local police spokeswoman Dana Ladmanova said.
No-one from the Thai embassy in Prague was immediately contactable.