They all managed to escape without serious injury when the snow-laden roof of the sports hall in Ceska Trebova began giving way on Saturday, local news agency CTK reported.
Two boys who were taking part in the tournament were treated for slight injuries.
The arena, 180km (110 miles) east of Prague, was hosting its first event since building work was completed on Jan 2, at a cost of 58 million Czech crowns (1.9 million pounds).
The architect who designed the arena denied the 25 cm of snow on the roof could have caused the collapse, local media said.
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(Reporting by Robert Muller. Writing by Patrick Johnston. Editing by Larry King)
