Fifteen people have been moved out of a Lowestoft care home after an inspection by environmental health officers.
Suffolk County Council inspected Orme House on Kirkley Cliff Road and described conditions as "simply unacceptable".
The residents have been moved to council-run and private care homes.
The local authority has not revealed what the problems are, but said it was carrying out an investigation alongside Suffolk Police.
A Suffolk County Council spokesperson said: "As soon as we were alerted to the situation we, along with our partners, took immediate action to ensure the well-being of all residents at the home - that was our immediate concern.
"These conditions are simply unacceptable and we are carrying out an investigation to identify the full extent of the situation.
"We are working with residents and their families to help them move out of the home and consider future options."
A Suffolk Police spokesman said officers will "conduct investigations to see if any offences have been committed at the home".
Anglia Care Homes Limited, the owner of Orme House and based in Colchester, Essex, has been unavailable for comment.
The care home was last inspected by the Care Quality Commission in April 2011, when it said all standards were being met.