Bank Holiday visitors to a popular zoo in East Anglia were evacuated from the attraction after the incident.
Bosses shut Hamerton Zoo in Huntingdon, Cambridgeshire at around 11.30am today over reports of a serious incident.
Cambs police have now confirmed that a female zookeeper has died after an attack by a tiger.
The zoo confirmed it would remain closed on Tuesday while the investigation continues.
Cambridgeshire Constabulary said the tiger involved was believed to be fine.
A spokesman said: “Officers attended a serious incident at Hamerton Zoo Park, Steeple Girding, at around 11.15am today.
“A tiger had entered an enclosure with a keeper. Sadly the female zoo keeper died at the scene.
“At no time did the animal escape from the enclosure. The incident is not believed to be suspicious.”
Multiple emergency service vehicles, including a number of ambulances, police cars and the Magpas air ambulance were sent to the scene.
The air ambulance landed at approximately 11.34am today.
Eyewitness Jeff Knott, from Cambridgeshire, said staff had been “a real credit” to the zoo during the evacuation.
The 32-year-old told the Press Association: “We had been in the zoo since about 10.30am and heard/seen nothing until asked to leave about 11.45am.
“Staff were very calm and professional. All visitors around us were leaving in a very calm manner - no running, shouting or anything similar.”
A spokesman for Cambridgeshire police said previously: “Officers were called at around 11.15am to reports of a serious incident at Hamerton Zoo Park. Officers attended the scene along with ambulance crews and MAGPAS.
“We are unable to provide any further information at this time, however, we can confirm that no animals have escaped and members of the public are safe. We will provide a further update when we are able to.”
A spokesman for Magpas added: “At 11.34am today, the Magpas enhanced medical team were called to a very serious incident.
“An East of England Ambulance Service paramedic crew and two rapid response vehicles were also in attendance, alongside the police.”
The zoo spans over 25 acres and has around 500 animals.
These include big cats, raccoons, sloths, Malaysian and white tigers as well as cheetahs and monkeys.
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