Teen Surfer Killed In Shark Attack In Front Of Dad In Australia

A teenage surfer tragically died on Thursday after he was mauled by a shark in South Australia ... and a witness says the horrifying incident all went down right in front of the boy's father.

South Australia Police said in a statement they received reports of the attack at around 1:30 PM at Ethel Beach in the Innes National Park ... but, sadly, when medics arrived on the scene, they said the boy had passed.

A bystander at the beach told the Adelaide Advertiser ... the teen had been out in the water with his father catching waves -- when a shark suddenly took his leg.

"Another local guy ran out, jumped on his board, and paddled out to help him," the witness told the outlet.

"The shark was circling them as the guy pulled the boy out of the water. There was a lot of blood. He brought him to shore but I think it was too late by then."

Tragically, this is the fifth reported shark attack this year in South Australia ... and sightings of the sea creatures have been common in the area recently.

In fact, a teacher was just killed by a shark at Walkers Rock in May -- which is just west of where the teen died Thursday.