Sydney City Local Area Command Superintendent Paul Pisanos said the police officers put their own welfare on the line to try and extinguish a volatile fire and save lives.
Superintendent Pisanos said the trio "effectively have been burnt alive".
"Unfortunately they were unable to achieve it so I imagine today they are pondering over their own actions and whether they could've done more, which is quite unfortunate really," he said.
He was confident emergency services did all they could to save the three victims, he added.
The surviving man is fighting for his life in St Vincent's Hospital.
Police said he broke most of his ribs, suffered extensive head injuries and had a brain bleed.
The other three victims haven't been identified.
"The sad part about it is...somewhere I would imagine across Sydney there are people waking up, their sons and daughter haven't arrived home from a night out in the city," Superintendent Pisanos said.
"At this stage there are probably people out there that don't even realise yet that they have lost a son or daughter or a brother or sister in relation to a car accident."
It was quite clear considerable speed was involved, Superintendent Pisanos added.
Shaken witnesses have recalled hearing screams coming from the smashed car as police and bystanders tried to save those inside.
Novotel Rockford guest Sonia Ripepi was woken by a huge bang and saw the car flipped over on the street outside her window.
"Then a taxi driver pulled over and he jumped out trying to get the passengers out," she said.
"He was screaming 'get out, get out'.
"He pulled one guy out of the car before it was engulfed in flames.
"The taxi driver was really distressed, he couldn't get any closer to the car.
"There was lots of screams still coming out of the car."
Ms Ripepi said it was only a matter of minutes before the car was completely engulfed in flames.
Peter Sergeant was also staying at the hotel when he was woken up and told to evacuate immediately.
"It was around 3am there was a great bang," he said.
"I thought it might have been an explosion and then I saw the fire below my window.
"We saw a group of people dragging someone along the footpath so I assumed it was someone injured.
"He wasn't conscious, I wasn't even sure he was alive."
Michael Coleman said he thought there was a fight happening outside the hotel because of all the yelling.
"...there was a lot of blokes yelling and agro sort of voices," he said.
"I went over to the window to have a look, thinking there was a fight or something, and I heard the car screeching and crashed I tot he building.
"I didn't realise it was actually on fire until we walked (downstairs) and you could see the car on its roof."
The blackened wreckage of the car was towed from the busy intersection about 11am after forensic police spent several hours examining the damage.
Police say it is still not clear what the relationship was between the occupants and who was driving.
