An unidentified male has survived attack by a shark at Fish Hoek beach, South of Cape Town, the National Sea Rescue Institute reports.

Tweets by journalists Paula Chowles and Dan Calders indicate that the man is in a critical condition, and is being treated at the scene. The victim was swimming at the time of the attack, and has lost his leg. He will be airlifted to hospital.

The following video was filmed by residents of Highhway Road, in Fish Hoek, and was lifted from News24.

A shark is clearly visible in the water off the beach, making the likelihood the self-same shark is responsible for the attack, very high. Surfers and bathers are advised to stay out of the water along the whole of the False Bay coast. Unconfirmed reports are that the advanced warning sirens usually used to warn of shark activity could not be sounded, due to an extended power failure earlier in the day. [Update: Authorities have refuted these reports, stating that the sirens are battery powered, and that due warning of the shark’s presence was given.]

More details to follow.