Family of black bears chases tourists in Yellowstone National Park

'Keep going!': Tourists ran as a mother bear chased after them with her brood in Yellowstone National Park

    

Cute, small and fluffy, these little black bears seemed to melt the hearts of visitors at Yellowstone National Park this week.

But their cooing soon turned into screams when the mother sow decided she'd had enough.

She started to chase, followed by her brood, and the tourists were forced to run.

'Keep going! Go! Go!' park ranger John Kerr shouts at the families as they leg it across a bridge in the Montana sanctuary.

At one point, one of the 13-month-old bears targets a teenage girl and follows her round the back of a car - before she jumps in the passenger's side.

And an elderly couple grip each others hands as they move as fast as possible.

Although the scene seems somewhat scattered and slow-paced, experts insist anything could have happened.

Had the bears been under the age of one year, the mother would have been relentless.

'These tourists were absolutely in danger,' Bob Gibson, Montana Fish, Wildlife, and Parks Communication & Education Program Manager, told NBC News.

'Black bears are usually shy of people. But you put them with their cubs and they get really protective. You never want to be between a bear and its cub.'

Officials said they were in no doubt that the tourists were in danger as they fled the bears