Emergency services were called to the National Zoo and Aquarium in central Canberra about 12.50pm on Monday after people heard loud screams, ACT Police Detective Superintendent Hall O'Meagher said.
Officers found the 29-year-old zoo employee dead with stab wounds in a store room out the back of a commercial kitchen. A knife was found at the scene.
A 29-year-old man, the woman's co-worker, was taken to hospital in a stable condition with self-inflicted wounds under police guard.
Det Supt O'Meagher said it was unknown at this stage if the pair were in a relationship.
"The investigating police have spoken to the family of the deceased and our thoughts are with them at this very difficult time," he said.
Charges are yet to be laid as police undertake a homicide investigation.
The zoo has been closed and it is not known when it will reopen, but police do not believe there is an ongoing threat to the public.
Acting Opposition Leader Sussan Ley described the death as "another horrific tragedy".
"As a woman I am angry, and I am shattered," she said.
"More than 60 women have already been killed by someone they know this year. Enough.
"This is a national crisis. We must stop this violence."
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