A woman has been arrested on suspicion of murder after three children were found dead at a house in Bristol. Avon and Somerset Police made the discovery when officers attended a concern for welfare call in Blaise Walk, Sea Mills, at about 00:40 GMT. A statement from the force said the young children were pronounced dead at the scene. The arrested woman, 42, is in police custody at a hospital. The force said the Independent Office for Police Conduct (IOPC) had been informed due to "prior police contact". Ch Insp Vicks Hayward-Melen said: "This is an incredibly tragic and heartbreaking incident in which three children have sadly died. "My sincere condolences go to the children"s loved ones, and we will be ensuring they are offered support through our family liaison unit. "We believe this to be an isolated incident and there is no further risk to the wider community." The IOPC said it had been notified of the incident by Avon and Somerset Police, with the force saying there had been prior police contact earlier this month. A spokesperson added: "We have requested a paper referral with further information about the prior contact and once received, we will assess it to determine whether further action is required from us." Mark Shelford, Avon and Somerset Police and Crime Commissioner, said questions needed to be asked about how "such an appalling event has occurred". "I am deeply saddened by the news of the deaths of three children today in Sea Mills," he said. "The deaths of these children is heartbreaking. My thoughts are with all those who knew and cared for these children and with the local community, who I know will be impacted. "The police have made an arrest and believe this to be an isolated incident. They have assessed that there is no further risk to the wider community. "There are questions to be asked about how such an appalling event has occurred and what could have been done to prevent it, but for now, I ask that people allow the police to investigate." Bristol North West MP Darren Jones said he was "deeply saddened by the tragic news from Sea Mills today". He added: "My thoughts and prayers are with the friends and family of the children, and my thanks go to our emergency services who responded." The city"s mayor Marvin Rees said: "It"s almost impossible to find the words to describe this afternoon"s devastating news. "My thoughts are with all who knew these three young children. "We will be working with schools, the community, and Avon and Somerset Police to support people." West of England Metro Mayor Dan Norris said the news was "tragic and heartbreaking". "My thoughts are very much with those who knew and loved these children," he said. "I cannot image the pain and shock they are feeling." — BBC