A highway patrol car was travelling more than 120km/h without flashing lights or sirens when it T-boned another car in a crash that's left a Sydney woman in a coma.
NSW Police confirmed the details a day after Gai Vieira's family made an emotional plea for a statewide ban on high-speed pursuits.
Ms Vieira was critically injured in the collision at a Cronulla intersection on August 5. Her two-year-old grandson escaped unhurt.
Assistant Commissioner Michael Corboy on Friday said the incident was "regrettable" and police were taking it very seriously.
"Police officers do not wake up in the morning thinking they're going to be involved in crashes," he told reporters in Sydney.
"We don't want this to happen and we want the community to be safe.
"The critical investigation team will be investigating the fact ... the lights and sirens were off (and) whether it was reasonable."
The assistant commissioner said in some circumstances police could conduct pursuits without lights and sirens.
He said the patrol car - which was chasing another driver who was allegedly using a mobile phone - clocked 124km/h in a 70 zone before the crash.
Investigators have already spoken to a dozen witnesses and are trawling through airbag data, in-car and dashcam footage, as well as NSW Police's automatic number-plate recognition system to identify cars around at the time to work out exactly what happened.
Mr Corboy said the collision was "complicated" and he'd not speculate if criminal charges could be laid.
Ms Vieira's husband of 43 years, racehorse owner Bert Vieira, on Thursday promised to dedicate his life to stopping high-speed pursuits in NSW.
In an emotional plea, he told reporters his wife "never stood a chance" in the collision.
"This should never have happened," he said through tears.
Mr Vieira wants NSW to ban or at least restrict high-speed police pursuits as is the case in Victoria and Queensland.
Mr Corboy on Friday said police were happy to offer any support to the family and address any concerns they have.
