Lions escape Sydney's Taronga Zoo, rescued and brought back to enclosure

Five lions broke free of their enclosure at Sydney's Taronga Zoo on Wednesday, prompting authorities to impose an emergency lockdown.

The lions -- one adult and four cubs -- were spotted outside their main enclosure at about 6.30 a.m., but were still separated from the rest of the zoo by a six-foot fence, 9 News quoted the facility's Executive Director Simon Duffy as saying.

A “code one” alert soon after sent the zoo into lockdown. Police were called at 7.10am and the lions returned to their enclosure just before 9am. A code one is the zoo’s most urgent alert, requiring an emergency response, the Guardian reported.

He said that 10 minutes had elapsed between the animals exiting the enclosure and the full emergency response being enacted.

While one of the cubs had to be tranquilised, the remaining four were returned to their enclosure "without issue", said the 9 News report.

Duffy said an investigation is underway to find out how the animals made their escape.

A loud duress alarm sounded soon after the discovery of the lions outside their normal enclosure prompted the lockdown, and could be heard by nearby residents.

A family who were staying overnight at the zoo as part of its luxury "roar and snore" programme told the Sydney Morning Herald they were told to "leave their tent and run".

In a statement, the Taronga Zoo said the situation is now under control and the zoo will open as normal.

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

In 2009, a lioness escaped its enclosure at Mogo Zoo, south of Sydney, and had to be shot dead because of the danger it posed to the public.