Description:A school of sharks in a feeding frenzy were filmed just a few hundreds meters offshore, north of Perth, Australia on Monday. The event, a natural phenomenon, was spotted by the crew of an air sea rescue helicopter with a camera. About 50 sharks were counted, including black tip whalers, bronze whalers and spinner sharks, some estimated to be 2.5m long. They were feeding on a school of tuna which were themselves feeding on a school of smaller fish.(0:56)