Three people have been arrested on suspicion of causing grievous bodily harm after a woman suffered serious injuries falling from a top floor window last night.
It is understood the woman fell from the top floor of the three-storey block.
Neighbours described hearing a "thud" before seeing paramedics treating the woman in the middle of the road.
Police arrested two men, aged 21 and 31, at the scene and a 42-year-old woman later this morning.
All three are being held at a south London police station.
The woman, who was treated by London Ambulance Service paramedics and a doctor from the London Air Ambulance, was taken to St George's Hospital in Tooting. It is understood she has yet to regain consciousness.
London Ambulance Service said it sent one ambulance crew, a first responder in a car and a duty officer to the scene.
Metropolitan Police officers are continuing to investigate the incident.
Sarah, 44, who did not want to give her surname, said: "We heard a thud, like something falling to the ground.
"It was around midnight, but we didn't think too much of it at first because it was a windy night.
"Then we saw the ambulances and thought maybe someone had been hit by a car or stabbed. You just don't think that's what it's going to be.
"We didn't hear anyone scream or anything.
"They were treating her about 30 minutes before they took her away. We heard a lot of crying. It was a female crying.
"It is horrible."
Alisha Shakespeare, 29, said: "I heard a noise, like a sort of bang. I didn't hear any sirens but I saw the ambulance and police outside.
"There were six paramedics treating someone right in the middle pf the road. That's when I knew it was serious because they obviously had to treat her right there and then.
"I thought maybe someone had been stabbed because it wouldn't be the first time we'd had trouble around here."
Anyone with information can contact Detective Sergeant Lee Hinton on 020 3276 2235 or call Crimestoppers anonymously on 0800 555 111.
Do you know more about this incident? Call the Croydon Guardian newsdesk on 0208 722 6351 or email firstname.lastname@example.org