A man has been arrested after four people were found dead in a house.
Derbyshire Police said they were called to an address on Chandos Crescent in Killamarsh, near Sheffield, around 7.25am Sunday.
Police said a man was in custody and were not looking for anyone else in connection with the deaths.
The relatives of the victims have been informed and are taken care of by specially trained agents.
Chief Detective Inspector Rob Routledge, who is leading the investigation, said: “We would really love to hear from anyone who saw or heard anything suspicious in the early hours of this morning, or has information they think could help us with our investigations.
“No matter how small you think this information may be, please contact us.
“This is naturally a worrying time for the community, and we would like to thank them for their patience and understanding at this time.
“It was important to us that relatives of those involved were informed before we could give more details about the incident.
“Residents will continue to see a strong police presence in the area, and patrols are being carried out to reassure themselves.
“If you have any concerns, please speak to them.”
Police urged anyone with information about the incident to come forward.