The Los Angeles County Department of Public Health reported 1,233 new cases and two new deaths in the last 24 hours, Xinhua news agency reported on Tuesday.

There are 528 infected people currently hospitalised in Los Angeles County.

On June 15, there were 218 people hospitalised, said the department, adding that test positivity increased 10-fold from the 0.4 per cent on June 15 to Monday's test positivity rate of 4.1 per cent.

Officials said the county is now beginning to see corresponding increases in hospitalisations after cases increased 700 per cent since June 15.

Los Angeles returned to mandatory mask-wearing indoors over the weekend.

The Los Angeles County Department of Public Health noted that they require all residents to wear masks in indoor public spaces, regardless of vaccination status.

"LA County continues to see alarming trends of increased community spread. The spread of the more infectious Delta variant through intermingling of unmasked individuals where vaccination status is unknown has caused a rapid spread of Covid-19 that is resulting in a significant increase in cases and hospitalisations," said Barbara Ferrer, the county's director of Public Health.

"By wearing masks indoors at public places and worksites, we can get back to slowing the spread of the virus," she added.

To date, the department has identified 1,269,090 positive cases with 24,585 deaths in the county, home to over 10 million residents and the most populous in the US.

Official data showed that among residents aged 16 and above in Los Angeles County, around 70 per cent of the population, have received at least one dose of a Covid-19 vaccine, and 62 per cent have been fully vaccinated.

But officials noted there are still almost 4 million people in the county who have not been or are not eligible to be vaccinated, including 1.3 million children under 12 years of age.