This is the moment beachgoers flee in terror after mistaking a pod of beached whales for a shoreline mass shark attack.

The footage was filmed at Prainha (Little Beach) in Arraial do Cabo, Brazil, on 31st December.

Many on the beach flee, screaming in terror as they see dorsal fins and huge tails thrashing around in the water.

The footage shows how some of the surf seems to have turned red as the sea creatures churn up the dark sand.

But experts have revealed that the panicked swimmers were almost certainly running away from a group of harmless whales.

Biologist Marcelo Tardelli told Brazilian media the species seen in the footage is probably the dwarf sperm whale (Kogia sima).

A town hall spokesperson said: “If confirmed, it is the first time this whale has appeared in Arraial and it is considered a rare species, being an important record for science.”

Some believe the white markings could make the whales harmless hourglass dolphins.

When officials later inspected the beach they found no beached whales, which they say probably managed to swim back out to sea.

They confirmed the animals were toothed whales (Odontoceti) and not sharks as some beachgoers had thought.

In the footage, some witnesses seem to be trying to help the stranded marine mammals.

But the Fundacao do Meio Ambiente (Environment Foundation) said people should avoid approaching or touching stranded animals.

It said: “In these cases, the most advisable thing is to wait for the arrival of specialised teams to help the animal.”

Authorities said there was a massive stranding of dolphins in the same location in 2012.