Swimmer Missing Following Suspected Shark Attack at Sorrento Beach

Emergency services are responding to reports of a suspected shark attack at Sorrento beach north of Perth.

St John WA received reports of the suspected attack at 10:15am local time and have confirmed three crews have been sent to the scene, including one on priority.

WA police are currently patrolling the beach, and officers could be seen standing along on the shoreline next to a red surfboard.

A police helicopter was also seen hovering overhead in the same spot.

The beach has been closed to swimmers and people are being advised to take caution.

A large group of people gathered on the beach path to watch the incident unfold.

Russell James was there when the shark alarm sounded.

"The helicopter was circling around and then the police boat came in," he told the ABC.

"There were a bunch of police and ambulances and a few people standing down by the water's edge near the groyne … there appeared to be a couple of surfboards or paddle boards down by the beach."

The suspected attack comes just a week after Surf Lifesaving WA's helicopter shark patrols began for the summer season.

Earlier, a member of the public reported seeing a 2.5 metre-long shark off the beach.

Sorrento is a popular swimming spot, located about 20 kilometres north of the CBD and just south of Hillarys marina which boasts multiple restaurants and cafes.