A week-old calf died in the fire

Paignton Zoo executive director Simon Tonge said there was a "one in a million chance" it could have happened.

The zoo's internal investigation found an emitter tube in the overhead electrical heater had fractured.

Three Rothschild giraffes, including a week-old calf, died but two elephants were saved in the 12 February fire.

Site visits

The inquiry by senior managers found zoo staff were professional and dealt with the incident well.

It took one hour to put out the fire.

Mr Tonge said: "Our maintenance schedule is comprehensive and our safety regime rigorous. Sometimes things happen that you simply cannot allow for.

"On the night of the tragedy Devon Fire & Rescue Service and Paignton Zoo staff did everything they could.

"They saved the lives of our two elephants, Gay and Duchess."

The lighting and heating equipment had been used for eight years but it is believed the emitter tube may have failed due to a manufacturing fault.

The inquiry recommended increased site visits from local fire crews to help familiarise firefighters with the zoo layout.