A woman and two children have been taken to hospital after a suspected poisoning at a house in Uckfield, East Sussex.
Emergency services were called to the address in Hunters Way over "welfare concerns" on Thursday morning, Sussex Police said.
Inside the property officers found a 38-year-old woman and two children - aged 9 and 13.
They were rushed to hospital and remain in a "serious but stable" condition, the force said.
A woman has been arrested on suspicion of administering a noxious substance or poison to cause injury.
Sussex Police said detectives were not searching for anyone else but inquiries were ongoing.
The force said the incident was being treated as "isolated" and there was "no threat to the wider community".