Joel Cauchi was experiencing psychotic symptoms when he armed himself with a 30-centimetre knife and rampaged through Sydney’s Bondi Junction Westfield on the afternoon of April 13, 2024.

Six people were killed and 10 others, including a nine-month-old girl, were injured before the 40-year-old was shot dead by police.

Critical care paramedic Christopher Wilkinson told an inquest into the tragic incident that crews were told to remain outside due to a “confused” conversation that suggested there was a second attacker.

The discussion with a police officer led him to believe the centre had been declared a “hot zone”, which meant paramedics couldn’t enter and provide life-saving assistance to injured people.

“I stood there with my boots on the ground quite frustrated that people may well be dying upstairs and no one is doing anything medically for them,” Wilkinson said.

Paramedics were prevented from entering the centre after critically injured security guard Faraz Tahir was brought out.

“I was left wondering whether there were any other patients like Mr Tahir,” Wilkinson said.

The area was officially declared a “hot zone” by NSW Ambulance at 4.30pm, despite police by then having clarified there was no second offender.

The declaration of a hot zone had no impact on the clinical outcome of any of the stabbing victims, the inquest was told.

A medical expert found all victims had already been treated by paramedics inside the centre by the time the hot zone was declared.

Communication effectiveness during the mass casualty event is one of the key topics being canvassed at the inquest.

Security officers also issued the wrong type of alert, telling customers to evacuate instead of warning that an armed offender was on the loose, Coroner Teresa O’Sullivan heard.

That alert, which flashed up on signage within the shopping centre, was only activated after Cauchi had been shot and killed by the first officer on the scene, Inspector Amy Scott.

A loud, related alarm also hampered communication between emergency responders on the ground.

Wilkinson, who has more than 40 years of experience as a paramedic and has been trained in dealing with mass-casualty events, said lives were lost when emergency services did not communicate effectively.

There were opportunities for improvement, he said, adding that paramedics did the best they could in a difficult situation.

“At Bondi, it made me very proud to be a paramedic,” Wilkinson said.

Dawn Singleton, 25, Ashlee Good, 38, Jade Young, 47, Pikria Darchia, 55, Yixuan Cheng, 27 and Tahir, 30, were killed in the April 2024 attack.

Cauchi had been diagnosed with schizophrenia as a teen and had been successfully treated until 2019 when he stopped his medication, the coroner previously heard.

He lived a largely transient life away from the support of his parents in Toowoomba, near Brisbane and had been homeless when he set foot into the shopping centre for the last time.

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