Two employees at the Calgary Zoo have been disciplined but not fired after an investigation into how some gorillas escaped their enclosure for the second time this year.

Late on Sunday afternoon, some of the zoo's gorillas accessed a secondary containment area known as the keeper kitchen next to their enclosure in the TransAlta Rainforest building. 

It's the same kitchen a group of gorillas broke into back in March after a door was left unlatched.

A zoo employee was injured after he startled the troop’s biggest gorilla, a roughly 455-pound silverback named Kakinga. 

The animal keeper would later lose his job after the zoo conducted an investigation.

The zoo says the kitchen door to the enclosure was left open on Sunday.

"We want to make sure that people know we take these things extremely seriously and so we'll take whatever appropriate actions we need," said zoo spokesperson Trish Exton-Parder.

The zoo says it is going to look at whether further safeguards are needed.