Ms Birrer, one of just six paramedics stationed in Condobolin in western NSW, travelled nearly 100km to Lake Cargelligo on January 22, after a gunman killed three people, along with an unborn child, and injured one other person.
Her adrenaline was pumping as she approached the isolated outpost on the edge of a vast lake.
"It was very chaotic, it was quite dangerous," Ms Birrer told reporters on Thursday after a NSW Ambulance ceremony honouring her courage.
"You don't really think about ... the danger.
"You just kind of go in and hope ... you can help your colleague and just do the best you can."
Julian Ingram murdered his former partner Sophie Quinn, 25, and John Harris, 32, as they sat in a car that summer afternoon.
Ms Quinn's unborn son also died.
Soon after, Ingram murdered Ms Quinn's 50-year-old aunt Nerida Quinn at her home, where 19-year-old Kaleb Macqueen was also shot and injured.
Ingram, a council gardener, was found dead in bushland 109 days later with a self-inflicted gunshot wound.
Ms Birrer was honoured with a NSW Ambulance award in Orange, in the state's central-west, for racing to assist her colleague and the victims in a "highly unpredictable environment".
It was a bittersweet award after a tragic day, she said.
"We're very privileged in these regional areas, they're so tight-knit and everyone really gets around you and supports you."
In another award, Muhammad Taha was given a community medal for his courage in confronting a knife-wielding attacker who killed six people at the Westfield shopping centre in Bondi Junction on April 13, 2024.
The security guard and his colleague Faraz Tahir were stabbed when they confronted Joel Cauchi as he attacked shoppers.
Mr Tahir suffered fatal wounds.
While critically injured, Mr Taha provided critical information about Cauchi's movements to the security control centre.
Cauchi, who was living with schizophrenia and was psychotic, was fatally shot by police officer Amy Scott.
Mr Taha, who also received an Australian Bravery Decoration in April, said he continued to be haunted by memories of that day.
"The only thing was the safety of others, without really thinking of ourselves," Mr Taha said of his and Mr Tahir's actions.
"It was a very sad day because I lost my colleague."
His extended family travelled from Pakistan to proudly watch as he received the latest honour.
Mr Taha, who was granted permanent residency after the attack, said he hoped to continue helping others.
"I am thinking of joining some community services, so I can be a part of the community and serve the community in the best way I can."
Lifeline 13 11 14
beyondblue 1300 22 4636
1800 RESPECT (1800 737 732)
Men's Referral Service 1300 766 491
6°C