Representatives of a charity which looked after a teenager found dead in a park in Newtownards have described her as a "loveable child".
Staff at Barnardo's, who cared for 15-year-old Darlene Bell when she was younger, said they were "devastated".
Prior to her death on Monday, she had been staying at Ashgrove residential care home for young people, a non-secure unit in the town.
It is understood that she had been abusing solvents.
From the age of eight, Darlene Bell stayed in a Barnardo's facility which looks after children while foster parents are sought.
The director of the charity, Lynda Wilson, said she knew Darlene well.
She added: "She was a bright spark of a little girl and a very loveable child. Our staff loved her very much and they are devastated by her death."
Fionnuala McAndrew, director of social services with the Health and Social Care Board, said a review of what happened would be carried out.
"I feel that health and social services here are very open to a process which we call a case management review - a process of learning to make sure that if there are things that need to be done differently or to be reinforced, then the lessons will be learned."
It is understood that Darlene had spent some time in a secure unit, but several months ago had been moved to an intensive support unit which gives young people more freedom.
BBC Northern Ireland health correspondent Marie-Louise Connolly said some politicians had called for an inquiry into how the tragedy had happened.
She added: "Some of those who work in the system say that often risks need to be taken to allow young people to live independently."
The South Eastern Health and Social Care Trust said it regretted the "sad and untimely death" of the teenager.
Kate Thompson, the trust's director of children's services, offered her condolences to the girl's family "at this sad time".
Strangford MP, Jim Shannon, said there was shock and disbelief in Newtownards at what had happened.
"The fact that someone so young should be found dead and alone in a park off the centre of town has sent shockwaves into the local community," he said.
"We are very shocked and very annoyed and everyone asks the question why and how could it happen?"
Mr Shannon said he had visted Ashgrove residential care home in the past and said it was "well-respected" and the staff were "very experienced".
"I think what we are seeking to do as a result of this is to take some action within the community," he added.
"I have had meetings with police and some of the other organisations to try and ensure we have an action or a programme to prevent this ever happening again."
Newtownards councillor, Terry Williams, worked in residential care units like Ashgrove for two decades, and described the nature of the environment.
"The supervision of the staff in any residential unit in Northern Ireland is of extremely high quality," he said.
"The difficulty that the staff are faced with is that they are not allowed under the law to restrict a child's movements - whether that is by holding them, locking the door or blocking the door, so these children will always have open access to leave."