One man immediately flees upon coming face to face with the bear, but three others climb in next to the animal's cage. Three other men help the migrants climb into the truck and close the door behind them.
French police said the men were in the truck for about 10 minutes before officers arrived to arrest them. They said the men were trying to smuggle themselves into Britain.
"Obviously he was in a crate, so it was all very safe and secure, but I think they were a bit surprised when they saw a polar bear," Yorkshire Wildlife Park spokesman Simon Marsh told the BBC. "It's not probably what they were expecting when they opened the back of the lorry. Even at two years old he's a big animal and he can be very dangerous. I think a lot of people in Calais would have been in trouble if he hadn't been in his crate."
The Yorkshire Wildlife Park said Nissan arrived safely at the facility, which houses two other polar bears.
