A Sumatran tiger gave birth to triplets at Chester Zoo in England, adding a few more lives to one of the rarest big cat species in the world.

The tiger cubs are three weeks old, but just emerged from their den for the first time a few days ago followed by their proud mom Kirana, 8. They also live with their dad, 7-year-old Fabi.

"Sumatran tigers are one of the rarest big cat species in the world. That's what makes our new tiger trio so incredibly special - they're a rare boost to an animal that's critically endangered," Tim Rowlands, curator of mammals at Chester Zoo said in a news release. "It's still early days but Kirana is an experienced mum and she's keeping her cubs very well protected. She's doing everything we would hope at this stage."

Sumatran tigers are endangered, as they are often targeted by poachers who use their body parts as traditional medicine and much of their jungle habitat has been destroyed, according to Chester Zoo. There are only about 300-400 Sumatran tigers left in the wild.

This tiger species only live on the Indonesian islands of Sumatra. They are also the smallest of all tigers and don the narrowest stripes.

The sexes of the tigers will not be known for a couple of weeks. Once the sexes are determined the zoo will name them.

Below is a video that captures the tiger triplets' first moments from a hidden camera in their den at Chester Zoo: