Police said the accident, which they believe was caused by the explosion of a compressed air canister on Friday night, injured one person severely, three seriously, and the others slightly, German news agency dpa reported. Police were still on the scene to investigate the cause on Saturday.
Several people were taken to nearby hospitals by helicopter.
The accident took place behind a pit in the track's paddock area during a test and set-up run ahead of the NLS4 race, officials at the track in the West German town of Nuerberg said in a statement.
Organizers said the NLS24 race would go ahead after consultation with all parties involved, but said participation was voluntary.
SD/PR