Two motorists and their Tesla plunged into a freezing fjord after the driver "accidently hit the gas", onlookers claim.

Video shows emergency workers hauling the car out of the water in Oslo, Norway, after the "screaming" occupants were rescued by a passing floating sauna.

Onlookers said the car quickly began to sink forcing the occupants - a man and a woman - to climb onto the roof.

But the vehicle disappeared below the waterline and they were in the water for a few minutes before they were picked up by the passing sauna at around 3.30pm yesterday (1).

Local Vladislav Nikiforov, 51, speculated the couple were there to watch the sunset.

The environmental NGO worker, who was out for a sunset walk at the time, said: "The driver he said he forgot to put it on parking and he pushed the gas - I don't know why.

"I guess he thought he was not afraid to push the gas as he thought it was in park."

He said the car "jumped" over a barrier in front of the water.

Speaking of the rescue, he added: "The car was under the water before the sauna came to them.

"They had to swim. It's incredibly cold, icy water.

"I don't think people could hold there more than five minutes in this water, especially with clothes on. It was very good luck this floating sauna was nearby.

"I think they were only in the water for a couple of minutes.

"The girl was screaming. She was very desperate."

Vladislav said divers went into the water to attach ropes before the car was pulled out.

"They took it out, had a look, and put it back in the water because they were afraid of fires," he said.