A retired married couple was stabbed to death and dumped in a crocodile-infested river in a South African national park, with police suspecting they may have been killed for interrupting poachers.

Ernst Marais, 71, and his wife Dina, 73, were found with multiple stab wounds and their hands bound behind their backs early Friday in the Limpopo River inside Kruger National Park.

Their bodies were discovered by a group of horrified tourists who were watching a herd of elephants cross the 7,579-square-mile reserve.

The couple had driven more than 1,100 miles from their retirement village in Mossel Bay to spend a week at the famous park. A search had already been launched after they were reported missing on Thursday morning by a maid at their safari camp.

“It was hoped that they had gone off the road and broken down somewhere due to heavy local floods, but then we received a call saying two bodies had been found,” a national park source said.

“Both had been stabbed in what was clearly a very brutal attack and were thrown into the river, no doubt for the crocodiles,” the source added. Their four-by-four vehicle was also stolen.

“This is a very major incident for us. This is an extremely safe national park and this has shocked us all.”

A South African police source believes the couple may have stumbled upon a ruthless group of poachers, who allegedly killed them to prevent them from alerting others to their illegal operation.

The source alleges the killers repeatedly stabbed the couple in the upper body, tied their hands behind their backs, dragged them to the river, and dumped them in the water.

“Their pick-up truck would have been an easy way to transport anything they were carrying if they were smugglers, and there are unfenced areas where they could cross the river into Mozambique,” the source said.

“A large manhunt is underway, based on the assumption that the suspects have already left the Kruger area.”

A devastated neighbor said the couple loved going on safari and owned another home on a wildlife estate near Kruger, known as the Valley of the Elephants, which they visited regularly.

She recalled police knocking on the couple’s door Friday morning before their bodies were discovered.

“The police came knocking on their door Friday morning to see if they had returned from Kruger early, and then we heard that Ernst and Dina had been found dead,” the neighbor said.

“They were a lovely couple who loved going on safari, and the residents are all in shock.”