A sports car plowed into a crowd of Mardi Gras revelers leaving a downtown parade in New Orleans and injured 20 people, police said. There was no immediate report on the extent of injuries, but police said several people appeared to have broken bones. The man driving the car was arrested at the scene and "will be tested to see if he had been drinking," a police spokesman said. The accident marred a cold but otherwise mellow Mardi Gras celebration as revelers refused to let near-freezing temperatures interfere with the annual affair. Police estimated up to 2 million people entered New Orleans for the festivities.