A suspected drink driver ploughed his pick-up truck into a crowd watching a Mardi Gras parade, injuring 28 people including children and a police officer.
Twenty-one people were taken to hospital after the crash at the Krewe of Endymion parade in New Orleans, five of them in a “guarded” condition.
The victims’ ages ranged from three or four to people in their 30s and 40s, said city emergency services director Dr Jeff Selder.
Mr Harrison said the injured police officer was undergoing tests and in “good spirits”.
One woman at the scene told The New Orleans Advocate that a truck whisked by her just feet away.
Carrie Kinsella said: “I felt a rush, it was so fast.”
Kourtney McKinnis, 20, told the Advocate that the driver of the truck seemed almost unaware of what he had just done.