Two children and a man have been found dead in a house in Hinckley after reports of a disturbance.
Leicestershire Police attended the address in Welwyn Road at 9.30pm on Tuesday after calls from concerned residents.
Contact was made with a man and woman in the house.
In the early hours of Wednesday morning a woman, who was found to have been injured, was taken to hospital.
Officers are not looking for anyone else in connection with the incident.
Negotiators and specialist officers were sent to the scene on Tuesday night, but when police gained access to the house a man was found dead in the property.
A search of the property also uncovered the bodies of two children.
Forensic examinations are being carried out at the scene, and the cause of death is not yet known.
Welwyn Road remains cordoned off at its junction with Glebe Road and Trevor Road and is likely to remain so for some time yet.
As officers had been in contact with the man and the woman, the Independent Police Complaints Commission has been informed.
Detective Chief Superintendent David Sandall, head of Leicestershire Police's crime and intelligence directorate, said: "A number of inquiries are now under way to understand what caused the three deaths, and the circumstances surrounding the events of last night in the house.
"Whilst we are not, at this stage, looking for anyone in connection with what happened, we would like to hear from anyone who may have information for us."
Anyone with information is asked to call 101 quoting incident 748 of November 1 2016.