The National Weather Service issued high surf advisories Thursday morning for Northern California, with 20-to-30-foot waves expected through Sunday.

LOS ANGELES — Northern California is bracing for another day of deadly waves topping 40 feet Tuesday as officials in Santa Cruz search for survivors and assess the damage from a partial collapse of the city’s landmark pier.

Three people were rescued from the wharf. The powerful surf also fatally trapped a man under debris on a beach in Santa Cruz, the authorities said.

Persistent high surf and flooding threats along California’s coast have residents on high alert a day after a major storm was blamed for one man’s death and the partial collapse of a pier, which propelled three people into the Pacific Ocean.

A witness, just 20 yards away, recounted the moments when several massive waves slammed into the pilings of the Santa Cruz Wharf, sending the end of the wharf and three people into the ocean.