An 'aggressive' great white shark was spotted by beach-goers off the California coast with experts warning it was hungry and hunting for seals. 

The shark was spotted by a foil board surfer who saw it circling about 300 feet from shore at 3pm on October 13, according to the Huntington Beach Fire Department.

'Huntington Beach Marine Safety has received a credible report of a 10-12 foot great white shark near Lifeguard Tower 16,' the fire department wrote in a Facebook statement. 

'The shark was reportedly circling, a behavior classified as aggressive under Marine Safety's shark response protocols,' the statement said. 

The water at Huntington Beach was closed from Sea Point Street to Huntington Beach Pier for safety precautions. Visitors were allowed to remain on the sand but were told to stay out of the ocean. 

Cal State Long Beach Shark Lab Director Chris Lowe told the LA Times that the great white might have been hunting for elephant seals. 

Lowe reported that he sent researchers to verify the sighting on Wednesday using a drone, a jet ski and a rescue boat but did not find the shark. He reassured that the surfer was 'a credible source.' 

Marine safety authorities confirmed that the surfer who reported the shark was not attacked or injured. 

The shark sighting at Huntington Beach has marked the second of the year as another one was seen in spring, prompting a 24-hour closure.

According to the Department of Fish and Wildlife, shark sightings in California have surged since June.

Experts have anticipated 'a larger presence of white sharks in Southern California as a result of warmer El Niño ocean conditions.' This refers to a climate pattern with warmer water in the central and eastern tropical Pacific Ocean. 

Lowe told the Los Angeles Times that the waters near Southern California have been home to juvenile white sharks about five to ten feet in length.

He explained that juvenile white sharks enjoy spending their time in ocean temperatures that are 'just right' and around 67-to-72 degrees Fahrenheit. 

'Forecasted warmer waters shift the preferred range for juvenile white sharks northward from Mexico and lead them to stay in California nearshore areas later in the year,' the Department of Fish and Wildlife wrote in a news release.  

Lowe told the outlet that even when beachgoers don't notice, the 'sharks are around people all the time' in the ocean. 

Local Californian residents have shared their reactions to the recent shark sightings on social media. 

'If you knew what swam under you when you swim in the ocean, you'd probably never get back in the water. There are so many sharks that pass under and near the surfers regularly that don't even bother anybody typically,' wrote one user. 

While another wrote: 'It's enough to keep me out of the water! Don't like 'em...don't want to ever see one with my own eyes. Nope...no thanks!' 

Fire department officials have advised California residents to stay safe and alert while the beach remains closed.

'Please follow all posted signs and instructions from lifeguards. Public safety remains our top priority,' the fire department wrote. 

The Daily Mail has reached out to Chris Lowe and the Huntington Beach Fire Department Marine Safety Division for comment.