Local residents have spoken of the horrific moment nine people, believed to be backpackers, were found in varying states of consciousness following a suspected mass drug overdose in a Victoria Park home.
Police were called to the home on Colombo Street just after 11pm on Tuesday evening, after reports people were "violently ill" at the home.
A WA Police spokesperson said on arrival, officers found up to nine people in semi-conscious and unconscious states.
Neighbour Sebastian Arevalo and his partner Sophie Barnett told Radio 6PR they witnessed people being wheeled from the home on stretchers.
'We were out at the movies and we came back at about 10.30," Ms Barnett said.
"We were sitting in the room over there, we heard this kind of... tapping, or banging. It did sound like it was coming from that house."
Mr Arevalo said the pair went out onto the street to investigate, and were shocked at what they witnessed.
"[The noise] warranted enough that we came outside to have a look and the next thing we knew there were just heaps and heaps of cops, ambulances and everything, it was really insane.
"About five minutes later we saw people coming out on stretchers, most of them were unconscious but one of them was having... a spasm and punching and kicking."
"The other was a bit violent, he was trying to get out of the bed and he was strapped down," Ms Barnett said.
"All of them you could tell they were not on this planet, they were off in their own world. It was so scary."
Police identified seven men and two women at the property, and said they believed their condition to be drug-related.
Three men were taken to Royal Perth Hospital, and two of them are now in the Intensive Care Unit in a critical condition.
Two men and a woman were taken to Sir Charles Gairdner Hospital, and two of them are also in ICU.
Another two men and a woman were discharged from Fiona Stanley Hospital on Wednesday morning.
WA Police said the group were in their 20s and were visitors to Western Australia.
The neighbours said they had witnessed a number of people coming and going from the property, and residents assumed it was a temporary hostel for international backpackers.
It's understood police and St John had previously been called to the property on December 30 for a minor incident.
Police are currently attempting to determine the identity of those affected, and the drugs found inside the property.
Anyone with information relating to the incident have been asked to contact Crime Stoppers on 1800 333 000 or make a report online.