A MAN is being investigated for suspected drink-driving after a pick-up truck slammed into a crowd watching a Mardi Gras weekend parade in New Orleans, injuring 28 people including children and a police officer.

Asked whether terrorism was suspected, police chief Michael Harrison did not say "No", but added that it looked like a case of driving while intoxicated.

"We suspect that that subject was highly intoxicated," he said.

Twenty-one people were taken to hospital after the crash, five of them seriously injured. Seven others declined hospital treatment.

The victims' ages ranged from three or four to people in their 30s and 40s, city emergency services director Dr Jeff Elder said.

Harrison said the injured police officer was undergoing tests and in "good spirits".

A woman who was among the crowd said a truck whisked by her just feet away. Carrie Kinsella said: "I felt a rush, it was so fast."

Kourtney McKinnis, 20, said the driver of the truck seemed almost unaware of what he had just done. "He was just kind of out of it," she said.

The accident came during one of the busiest nights of Mardi Gras when thousands of people throng the streets of Mid-City to watch the elaborate floats and clamour to catch beads and trinkets tossed from riders.

The accident scene was cordoned off with police barricades.