Unusually large waves are hitting California shores as powerful storms pass through the region, leaving at least eight people needing hospital treatment.

Waves over 20ft high poured over seawalls and the tops of low cliffs along the Pacific coast, flooding nearby streets and leaving many injured. In a video taken on Thursday morning by Ventura native Colin Hogue, people are seen fleeing Pierpont beach – just north of Los Angeles – as a monstrous rogue wave engulfs the area.

Hogue called the scene “horrific”.

“There was a lot of screaming, a lot of yelling, a lot of cussing. I didn’t know how far this was going to go,” Hogue said. “I thought to myself ‘this is a tsunami.’”

The Ventura county fire department reported eight people were transported to local hospitals after coming in close contact with the massive wave.

Andy Vansciver, a VCFD firefighter, told KTLA5: “I think a lot of lessons were learned today when you look at that video of the importance of heeding on to the warnings of giving the ocean some respect.”

Large debris has led to road closures in the path of the waves. As a result, a coastal flood advisory and a high surf warning are in effect until Friday for more than 6 million people in parts of California and Oregon.

Evacuation warnings were also issued in counties along the coast of the state, including Santa Cruz, Marin and Ventura.

In Santa Cruz, the local news station KSBW Action News 8 captured a powerful wave that flung two nearby children into a bush.

The worst is yet to come.

On Friday morning, the National Weather Service issued a warning: “Widespread precipitation will spread across the region today through Saturday, with the heaviest expected tonight. Be prepared for slick roads and a longer than normal commute. Slow down on wet roads! #cawx”