Many children were inside the building in the southern town of Bad Reichenhall when it collapsed on Monday.
Fritz Braun, a police spokesman said five bodies had been recovered. "Another person was rescued but subsequently died in hospital," he said. "Five more bodies have been seen but not yet recovered."
Rescue workers with heavy cranes and sniffer dogs struggled in heavy snow and freezing temperatures to reach survivors but authorities were preparing for more casualties.
"It's unfortunately deathly quiet in the hall," Braun said.
In one hopeful sign, a girl was rescued six hours after the roof collapsed at about 4pm local time on Monday.
"Another person was rescued but subsequently died in hospital. Five more bodies have been seen but not yet recovered"
Fritz Braun, police spokesman
Officials said that about 50 people were thought to have been in the sports complex when the roof collapsed. About 30 injured were rescued but it was unclear how many were still trapped inside the debris, officials said.
Another police spokesman, Hubertus Andrae, said: "The big unknown is how many people were actually on the ice at the time and how many may have been able to get out on their own."
German public television reported that state prosecutors were examining the case to see if charges of negligence should be brought.
Shortly before the roof collapsed, officials cancelled a training session of a local ice hockey team scheduled for the afternoon amid concern over the volume of snow building up.
But officials said that measurements had shown that the quantities of snow on the roof were within normally safe limits and there was no indication of any immediate safety threat.
German media reported that building problems had long been identified in the structure, dating from the 1970s.