Governing body FIA said the 31 were treated by Catalunya Circuit medical staff, with seven of those flown out to a variety of hospitals to receive more treatment.
The Catalan regional government said that one person was airlifted to hospital with serious burns, while five others were taken to a local hospital for the effects of smoke inhalation.
A couple of hours after Williams’ first win since 2004, something exploded in the British team’s garage, triggering a major fire.
Team members and fire crews battled the blaze as paddock regulars scrambled away from the heavy smoke and police arrived on the scene.
“The team, the fire services and the police are working to determine the root cause of the fire,” Williams said in astatement.
Update: Williams confirmed a fuel leak caused the problem.
The fire began in the area where fuel was stored, Williams added.
Mechanics from the Caterham and Force India teams helped Williams staff put out the flames, the FIA said. Press photographs showed the burnt-out racing car of Maldonado’s teammate Bruno Senna.
“The Williams F1 Team would like to thank all of the teams and the FIA for their support in today’s incident,” said the team in a statement.
The fire was the second in the Formula One paddock in five races this season, with one breaking out in the Lotus hospitality area at the Malaysian circuit in March.