Police failed to attend a 999 call made from a house where four people, including two young children, were subsequently found dead.
Norfolk police said it was contacted by a man at the address at about 6am on Friday but no officers were deployed.
About an hour later it received another call from a member of the public. This time officers were sent. They forced entry to the house at about 7.15am and found the bodies of two young girls, a 45-year-old man and a 36-year-old woman.
The force said on Saturday that it had referred itself to the Independent Office for Police Conduct in relation to its failure to attend the first 999 call.
It had already referred itself to the watchdog on Friday in relation to a separate matter linked to the case. Eleven days before Christmas, officers had been involved in a missing persons inquiry at the address in Costessey, near Norwich.
The four found dead are yet to be formally identified, but the man has been named locally as Bartlomiej Kuczynski, a Polish engineer. He is understood to have lived at the address with the two children, thought to be his daughters. Police said the woman found dead with them was visiting and lived elsewhere. They are believed to have been members of the same family.
DCI Chris Burgess, from the Norfolk and Suffolk major investigation team, said: “Postmortem examinations will be carried out tomorrow for the man and woman, and on Wednesday for the two girls.
“While I can confirm all four people were found with injuries, we will not be disclosing any further information until these examinations have taken place and the cause of death has been established.
“This is a tragic incident, distressing for all involved, and it is clear from the reaction it’s caused a lot of shock and upset in the local community. We’ve had uniformed officers patrolling the area today and these will continue tomorrow.”
Police confirmed they are not looking for anyone else in connection with the incident.
This weekend, neighbours left flowers and cards outside the house while local churches opened so people could light candles and pray.
Police were patrolling the area on Saturday with detectives carrying out house-to-house enquiries and reviewing CCTV. A cordon remained in place and forensic examinations were still under way.
The police watchdog confirmed it had received a referral from Norfolk Constabulary “in relation to prior contact the force had at the address in Costessey, near Norwich, where four people were sadly found dead”. “We are assessing the available information to determine whether an investigation into that contact may be required and if so, who should conduct that investigation,” an IOPC spokesperson said.
The force said the referral was made “following the identification of a 999 call made yesterday morning at 6am by a man at the address and police resources were not deployed”. The earlier referral was made “due to police contact at the address on 14 December which related to a missing person enquiry”.
Post-mortem examinations to establish cause of death will be held in due course.
