Five lions are back in captivity after escaping from their enclosure at Sydney’s Taronga Zoo on Wednesday morning, forcing staff to take refuge and placing the zoo into lockdown.

Taronga Zoo executive director Simon Duffy confirmed in a press conference that one lioness and four cubs were located outside their main enclosure at 6 am on Wednesday.

Mr Duffy said they had received video footage and told reporters “that it was less than 10 minutes between the lions exiting their main exhibit and the full emergency response”.

“This is a significant incident and a full review is now under way to confirm exactly how the lions were able to exit their main exhibit,” he said.

Mr Duffy said the lions were separated from the rest of Taronga Zoo by a six-foot fence, and that “at no time” did the lions exit the Zoo.

He said all the lions were safely back in their enclosure.

Four of the lions  “calmly made their way back their exhibits and dens” and one lion cub was safely tranquilised, Mr Duffy said.

“The zoo has very strict safety protocols in place for such an incident and immediate action was taken,” he said.

The lions will not return to the exhibit until the review is undertaken.

Earlier, Taronga issued a statement confirming the incident.

“An emergency situation occurred this morning at Taronga Zoo Sydney when five lions were located outside their enclosure,” it said.

Aerial footage showed keepers patrolling the ground during the emergency.

“The zoo has strict safety protocols in place for such an incident.

“All persons on site were moved to safe zones and there are no injuries to guests or staff.

“All animals are now in their exhibit where they are being closely monitored.”

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The zoo, at Mosman on the city’s north shore, will be open as normal on Wednesday.

Independent local newspaper the Mosman Collective reported that a “code one” was issued shortly after 7.30am on Wednesday.

“Staff were told to go to a safe haven,” the paper’s Facebook page says.

– with AAP