These remarkable pictures show the moment a motorist found himself in the middle of a race for life between a bison and a grizzly bear.

Unsuspecting Alex Wypyszinski stepped out of his car to take some scenic photographs in Yellowstone National Park, USA, when he suddenly found himself at the centre of the high speed chase.

The shocked post office worker had just dropped his wife off at work when he heard a galloping sound behind him.

The grizzly bares his teeth as he chases down a bison

The bison was badly injured from the encounter but managed to escape

He said: ‘At first I couldn’t work out what it was. It sounded like an old horse and carriage going past.

As his images show a bison was escaping a grizzly bear attacker.

‘When I turned around I couldn’t believe what I was seeing. I thought I was having an hallucination or something.

‘The bison was so beaten up I thought the bear must have been munching on it for ages.

Alex Wypyszinski had just stepped out of his car to take some scenic photographs when he witnessed the chase

While bison weigh more than twice as much as grizzly bears on average, the bear won this fight

‘But it was actually putting up a good fight and they were going 25 to 30 miles an hour when they ran past me.

‘I thought about jumping on top of the car at first but as they came closer I jumped into into the car and took some pictures through the window.

‘When I thought it was safe I got back out and carried on snapping.

The bison managed to escape the claws of the grizzly bear but was put down the following day by park rangers as his injuries were too severe.

While the bison was able to escape the bear after the attack, park rangers had to put it down the next day as the injuries were too severe