The Russian-made An-30 plane had 23 people on board -- 14 Russians and 9 Czechs, Czech military spokeswoman Jana Ruzickova said.
Russian Defense Ministry spokesman Col. Igor Konashenkov said the plane's front landing gear collapsed as it was touching down, an explanation Ruzickova declined to confirm. Czech public television footage showed the plane broken in two and gutted by fire.
Ruzickova said five Russians and one Czech national suffered injuries, mostly burns. One Russian national who suffered burns to 20 percent of his body was in life threatening condition, said Hana Vranova, spokeswoman for Prague's Vinohrady hospital.
The incident took place Wednesday at the Czech air force base in Caslav, some 20 miles east of Prague. The plane was on a mission sanctioned by the Open Sky treaty, which envisages surveillance flights over the territory of its participants, including NATO members, Russia and others.
A Czech military committee is investigating the crash.