Wildfires roared Sunday across much of California, forcing thousands to evacuate homes as the most populous US state sweltered in record heat and flames menaced thousands of structures.

Violence broke out at a pro-Donald Trump rally in southern California on Saturday when a masked man pepper-sprayed the female organiser before demonstrators tackled him to the ground.

Almost 200,000 people were under evacuation orders in northern California on Monday after a threat of catastrophic failure at the tallest dam in the United States.

A former high school student in California has been awarded $1.25 million for having been forced to urinate in a bucket after being denied a bathroom break.

California, home to many foreigners without residence papers, is girding to fight any attempt by President-elect Donald Trump to expel them.

A 6.5-magnitude earthquake struck Thursday off the US west coast north of San Francisco, but no major tsunami threat was expected, seismologists said.

The grisly search for bodies in the charred remains of a California warehouse will enter its third day Monday, with relatives of the missing being asked to provide DNA samples to speed up identification.

Fire crews in California worked into the night Saturday sifting through the remains of a warehouse gutted by a blaze during a rave party, with officials saying they fear the death toll could reach 40.

Authorities at two universities in California said Thursday police were investigating attacks against female Muslim students, one of which was described as a hate crime.

Two polling stations in California were placed on lockdown Tuesday following a nearby shooting that killed one person and wounded three, the authorities said.

An intruder was shot and a security guard stabbed during a break-in at the Malibu mansion of supermodel Miranda Kerr, police and local media reported.

Two US police officers were fatally shot and one injured Saturday while responding to a domestic disturbance call in Palm Springs, California, police said.