Governor Gavin Newsom tightened California's coronavirus lockdown on Monday, shutting parking lots at beaches and parks in the most populous US state after tens of thousands flouted social distancing rules over the weekend.

To slow the spread of COVID-19, the main Venice Beach parking lot is locked on Monday in Venice, California. Parking lots at many popular beaches including Venice and Santa Monica beaches are closed after crowds were seen on some beaches over this weekend during the coronavirus pandemic. Photo: AFP

The state is already under orders to stay home, but images of record crowds flocking to beaches such as Malibu and Santa Monica went viral on Sunday.

"I had a little anxiety, as all of you did, watching the news of all those folks and crowds in our parks, out there on the beautiful California coast," said Newsom.

"We're going to shut down all state parking lots" immediately, he added, saying "we can't see what we saw over the weekend happen again." 

California, one of the worst-hit US states, has more than 1,700 confirmed cases, including at least 27 deaths.

Newsom ordered on Thursday that all residents to stay home, barring essential activities, and to maintain social distancing. But the order will likely not be enforced by police, Newsom said, expressing hope that people would self-regulate.

"We need to help you help yourself, a little bit more, those folks that were making their way out" at the weekend, Newsom said on Monday, calling the new measure a "soft closure."

"To recognize when you're on a single-track trail out in our beautiful wilderness, that single track means going up the mountain, and down the mountain - which means it's almost impossible to socially distance.

"When you're out there and you can't even find parking at a beach, it suggests you're not going to practice social distancing, and it may suggest you may want to find a new location."

Meanwhile, Los Angeles Mayor Eric Garcetti loosened restrictions on restaurants delivering alcohol to people in their homes. Other US jurisdictions have made similar moves.

"This will not only be something nice for the people of LA, but good for those businesses to keep them alive, so that when this crisis is over your favorite neighborhood watering holes and restaurant will still, we hope, be there," he said.

Governor Newsom also praised entrepreneur Elon Musk for delivering 1,000 new ventilators to Los Angeles from where they will be distributed to hospitals, with fears that US medical facilities will not have enough of the crucial machines to cope with a surge of infections.