A vehicle ploughed into a crowd in Los Angeles on Sunday and injured nine people, one critically, authorities said, but it was not clear if the incident was intentional.

Eight people were being transported to hospitals after the vehicle struck the crowd on West Pico Boulevard, the Los Angeles Fire Department said on Twitter. A ninth person, an off-duty Los Angeles firefighter, was hurt but did not need to be taken to a hospital, it said.

A 44-year-old man was in critical condition, the fire department said. Three people were seriously injured, and four were in fair condition, with the ages of the seven ranging from 18 to 51, it said.

Los Angeles' NBC television affiliate, KNBC, said the vehicle was a van and the driver had remained at the scene.

The fire department tweets did not say if the incident was intentional. Militants mounted vehicle attacks in the past year on pedestrians in Britain, France, Germany, Israel and Sweden, and a man drove a van last month into a crowd of worshippers leaving a London mosque.