A vehicle rammed into people waiting to enter a nightclub along a busy boulevard in Los Angeles early Saturday, leaving at least 20 injured.

People were transported to local hospitals and trauma centres, according to Capt. Adam Van Gerpen, public information officer for the Los Angeles City Fire Department.

The precise number hurt varies, with different media citing between 20 and 30. 

At least three were in critical condition after they were injured along Santa Monica Boulevard in East Hollywood, the fire department said in a statement.

Van Gerpen said a line of people — the majority female — were waiting to enter a nightclub when they were struck by a Nissan Versa that also hit a taco truck and valet stand.

Paramedics discovered one of the patients had a gunshot wound, Van Gerpen said. He told The Associated Press the identity of that person was not yet known.

"This is under police investigation," he said. "This will be a large investigation with the LAPD."

Van Gerpen said people inside the club came out to help in the minutes before emergency crews arrived to tend to the injured.

"They were all standing in line going into a nightclub. There was a taco cart out there, so they were ... getting some food, waiting to go in. And there's also a valet line there," he said. "The valet podium was taken out, the taco truck was taken out, and then a large number of people were impacted by the vehicle."

Authorities gave no immediate details on the cause of the incident or the identity of the driver.