A man has been stabbed to death in Westfield Parramatta.
Police said emergency services were called to the shopping centre at about 10.30am, after reports a man had been assaulted.
Officers found the body of man inside the shopping centre.
Police believe the man suffered a stab wound.
A man has been arrested by police and taken to Parramatta Police Station where he is currently assisting with inquiries.
A worker in the shopping centre said she saw police tackle a man to the ground. She said the man ''was shirtless and looked off his head''.
She said the incident occurred in the cosmetic section of Myer on level four. The store is still closed to the public, as are the surrounding shops.
Myer employee Bianca Zoratto-Ivanov said a friend of hers saw the stabbing close to the entrance of the store's cosmetic section.
"He heard a scream, like a man yell," she said. "He heard it again and then he heard two young women scream: 'He's killing him! He's killing him.'
"That's when he turned around and saw the incident was taking place. He saw the man facing the store and doing the stabbing motions."
Ms Zoratto-Ivanov said she knew the employee at Aquila Shoes who had seen the offender drive a machete into the victim.
"The man had a big machete," she said.
"He saw glimpses of it, but turned around as soon as he saw.
"It wasn't in Myer, it was outside of Myer."
She said a number of women from the cosmetics section of Myer also saw the bloody stabbing and they were heard screaming.
A portion of level 5 and the upper level five carpark is also in lockdown.
Police have established a crime scene.
A Westfield spokeswoman said about 30 shops have been closed. The rest of the shopping centre remains open.
She said the centre is offering counselling to staff and customers. Anyone wishing to access this service should ask security, or at the Concierge Desk.
More to come.