The British newspaper The Sun reported 31 people were treated for burns and the effects of smoke.
As black smoke poured from the garage of Frank Williams' team, members pulled to safety the 70-year-old Formula 1 chief, who uses a wheelchair. He was not injured.
When the fire broke out, as.com (Comunicado de Prensa) reported, about 200 people were in the garage celebrating the victory of Venezuelan driver Pastor Maldonado, who carried his 12-year-old son to safety.
Sources said the most seriously injured person was a mechanic at the back of the garage, where the explosion happened.
Officials said a fuel rig being used to drain second driver Bruno Senna's car likely leaked before the fire broke out.
Seven fire units arrived at the track, and it took 20 minutes to bring the fire under control.