An orangutan climbed out of her enclosure at Perth Zoo to rescue her five-year-old boy Sungai after he lost his grip on some equipment and fell into a garden bed about 2.30pm on Sunday.

Amanda Oliver was at the zoo with her son, and tweeted it seemed the young orangutan had swung down to play with her son, before visitors to the zoo were evacuated to the safety of the nocturnal house.

"It was a bit scary once the mum jumped down," she said.

Zoo visitor Jess McConnell also witnessed the escape and managed to capture some video.