A 60-year-old woman has been arrested on suspicion of manslaughter by detectives investigating the deaths of three people at a care home in Dorset. Officers are still treating the deaths at the Gainsborough care home in Swanage as unexplained and have confirmed that “possible carbon monoxide poisoning” is the primary line of inquiry. Seven other residents were taken to hospital. But late on Wednesday night Dorset police revealed they had arrested a woman on suspicion of manslaughter and she remains in custody. DCI Neil Third, of the major crime investigation team, said the arrest was made “to enable us to establish whether there have been actions or omissions which are grossly negligent and gather as much information as we can about what has happened”. Dozens of other vulnerable residents were evacuated from the care home to a nearby church – some in wheelchairs and on stretchers – while places in other care homes were found for them. Police were called at 7.16am on Wednesday after the three people were found dead at the 48-bed care home in Ulwell Road. Police said the families of those who had died had been informed and the coroner had been notified. Earlier, Ch Supt Heather Dixey said: “Seven people have been taken to hospital as a precaution and other residents have been evacuated. The deaths are being treated as unexplained and we are continuing to work with our partner agencies to ascertain the full circumstances as to what has happened.” Dorset council said many of the residents were “vulnerable people with significant care needs”. The Rev Jo Levasier, team vicar at All Saints Church, where evacuated residents were taken, said many were very distressed. She said: “I got a phone call at 7.45am from the care home asking if we could help out and open up the building. About half an hour later people started arriving. Some came on stretchers, some came in wheelchairs. We have a few beds that have been set up. Quite a few people are confused. “The local community also got involved and were brilliant. People brought blankets, food, tea, coffee, and some people from the local school came down to talk to people. “We now hope to get everyone out of here by tonight. I don’t think they know what happened but they know they can’t go back to the home.” Salama Ghounaim, 34, who works in the kitchen at the home, said: “The decision was to take everybody out of the building to the church. The residents are all very elderly – some of them are almost 100 years old.” Charlotte Harris, 34, who used to work in the care home as an activities coordinator, and who saw the evacuation, said: “Some of the residents were bed-bound, so between the care staff and ambulance staff they were hoisting them into the ambulances. “When you do drills you never expect it will happen in real life. I just wanted to help. When you’ve got residents who have dementia they need a lot of care.” The church housing the evacuated care home residents received donations from businesses in Swanage throughout Wednesday. TA bakery gave boxes of pastries while a restaurant donated bags of fish and chips. The home is run by Agincare, a family-owned business founded in 1986 in Weymouth and now employing 4,000 people at more than 90 locations across England. A spokesperson for the home said: “The wellbeing of residents is always our overriding priority, and part of the local business continuity plan was to transfer residents in a managed way. We will continue to work with the lead local authority services to return residents into their home at the earliest opportunity.” The local gas company SGN confirmed there had been no mains gas leak at the property, which would support the theory that carbon monoxide poisoning was the cause. The Care Quality Commission rated the home “good” in a 2021 report, which said “risks within the home environment were robustly managed”. It quoted a relative as saying: “We don’t see anything unsafe. My [family member] was a fireman, and we were brought up with health and safety in mind, and we don’t spot anything unsafe.” Another said: “They are very safety conscious.” On its website the home says it “provides a safe and homely environment within a real village community, positioned within easy reach of the GP practice, village shop, bakery and cafes with the beautiful seafront just a short distance away”. The home’s Facebook page shows images of residents going on trips including to a tank museum, safari park and circus. There are also images of residents being entertained at the home by a violinist and of a visit from a therapy dog. The daughter of one of the residents who was evacuated safely described the staff as “fantastic” and said they would be devastated at what had happened. Carbon monoxide causes about 60 deaths and 200 hospital admissions every year in the UK, according to the West Yorkshire fire service.