A man, woman and two young girls from the same family have been found dead at a house.
Police forced entry to the home in Costessey, near Norwich, after a call from a concerned member of the public.
Norfolk Police said the bodies of the man, 45, woman, 36, and the girls were discovered inside, all with injuries.
Det Ch Insp Chris Burgess, who is leading the investigation, said three of the family lived at the address but “the woman involved was visiting”.
The identity of those who died will not yet be revealed.
Officers were called to Allan Bedford Crescent at about 07:15 GMT.
“I understand that news of this incident will be shocking to the local community and as soon as we can we will release more information,” Det Ch Insp Burgess said.
“Our investigation is in the very early stages and this is clearly a very distressing and tragic incident.”
‘Isolated incident’
A knife found in nearby woodland was not thought to be linked to the deaths, Det Ch Insp Burgess said.
He confirmed that officers were not currently investigating any other locations but would remain in Allan Bedford Crescent for a “considerable time”.
“I would reassure the local community that we’re doing everything we can to establish what happened at the address, I’m confident this is an isolated incident,” he added.
“I would urge people to be cautious around the information they share on social media, and between each other, we don’t want false information getting out there because that can frustrate the inquiry and cause undue distress where it’s not needed, so please rely on the information the police are sharing.”
Det Ch Insp Burgess confirmed that officers were called to the same house on 14 December as part of a missing persons inquiry and said that particular investigation would be re-examined.
“We want to get this absolutely right and the way we get it right is being detailed, accurate and taking our time to do so,” continued Det Ch Insp Burgess.
“We can confirm all four were found with injuries and post-mortem examinations will be held in due course to establish cause of death.”
He confirmed the family’s next of kin had been informed and were being supported.
Daniel Seeley lives on the estate, about 200-300 yds [185-275 metres] from the house.
Mr Seeley said he was “shocked, absolutely shocked” after seeing the news.
“It’s a quiet estate, things don’t happen around here like this,” he said.
Ms Blundell said she was “still in shock” and added: “It’s tragic. You don’t expect that on such a close-knit community.
“Our community is lovely and always there for each other.
Jocelyn Atienza, a neighbour, said she knew the family but only in passing as their children went to school together.
“I only met them sometimes in the street because my son and her kids go to the same school, so we met sometimes in school or in the street and said ‘hello’,” she said.
She said she was left “shaken” by the “sad and tragic” news.