Care inspectors have been at a residential home after three residents were taken to hospital, sparking concerns about safeguarding.
Paramedics responded to an emergency call from a resident at Kingswood care home in Worthing on Sunday and six ambulance vehicles were seen outside.
The BBC has been told paramedics found there was no heating.
The care home in Heene Road said it was working with the authorities and caring for residents.
The home provides services for people over the age of 65 with dementia.
West Sussex County Council (WSCC) said three people were taken to hospital.
A spokesman did not give details but said: "The welfare and safety of residents remains our highest priority.
"We continue to work closely with NHS partner organisations, other local authorities and the Care Quality Commission to ensure the wellbeing of residents.
"As the situation remains a live matter, we are not in a position to comment further at this stage."
James Frewin, head of adult social care inspection in the South East for the Care Quality Commission (CQC), said: "We have been made aware of some significant safeguarding concerns at Kingswood Home on Heene Road, Worthing.
"Inspectors visited the service on 17 and 18 February and have been working closely with WSCC and other stakeholders."
Sussex Police said officers were making inquiries about safeguarding concerns raised in relation to residents.
A spokesman for the force said: "We are working closely with WSCC social services who are responsible for any issues relating to care needs of residents, and with the CQC who are responsible for any issues relating to standards of accommodation."
A man who answered the mobile phone at the home, but did not give his name, said: "We are working with the authorities to ensure residents' welfare is taken care of.
"We are just putting every effort into working with the authorities to do everything we possibly can to make sure welfare needs are met."
He would not comment on details of the incident on Sunday, including the number of people involved.
According to the care home's website, its latest CQC rating was that it requires improvement.
South East Coast Ambulance Service confirmed paramedics responded to an emergency call for one resident at the home at 01:15 GMT on Sunday, but a spokeswoman was unable to give further details.
Both Sussex Police and WSCC said the incident was not related to the coronavirus, Covid-19, virus.