An American woman has been killed by a lion that jumped into a car and attacked her at a nature park in South Africa, according to reports.

The attack, at Lion Park outside Johannesburg, is said to have left another passenger of the car, a man, with serious injuries.

The pair may have been travelling in a car though the park with its windows open, according to the eNCA website.

The site quoted Scott Simpson, a manager at the lion park, as saying that the lion appears to have jumped into the car and bitten the woman. He added that the man was injured trying to protect the woman.

"Our staff working at the top of the camp tried to get the lion away from the car. Ambulances were called immediately but it was too late," Mr Simpson said.

Visitors to the park are told not to leave their windows open.

"We make it so clear.," Mr Simpson added. "We put signage up everywhere that people must keep their windows closed. We hand them a slip of paper when they enter the park, I really don’t understand why people think its okay to leave windows open."