Two children who died in a house in Stoke-on-Trent on Sunday have been named as Ethan John, 11, and Elizabeth John, seven.
The schools of both of the children paid tribute to them after they were found unresponsive with "significant injuries" inside a home on Flax Street on Sunday.
A 49-year-old woman from Stoke-on-Trent was arrested on suspicion of murder. She remained in custody on Monday evening being questioned by police.
Ethan's school said: "Ethan was a wonderful member of our school community. He had impeccable manners and an infectious smile. He will be hugely missed by the staff and pupils alike, and will forever be part of our hearts."
In a tribute to Elizabeth, her school said: "Elizabeth was a kind, caring and friendly member of our school family.
"She was a ray of sunshine who always had a smile on her face. She was everyone's friend - she was both bright and popular. The loss of Elizabeth is truly devastating for us all and her absence will leave a huge hole within our school community."
Detective Chief Inspector Cheryl Hannan, of Staffordshire Police, said: "I cannot begin to imagine the pain and suffering felt by the family and friends of these two children at this time.
"Specially-trained officers are continuing to support those closest to the children whilst we find out more about what happened yesterday afternoon.
"I'd like to thank those who have already come forward with information and to the local community who have been respecting the cordon in place on Flax Street.
"We are solely focused on finding out what happened to these two children and supporting those affected by this deeply traumatic incident."
Officers were first called to a car wash on Campbell Road just after 2pm on Sunday following reports of a fight between a man and a woman.
A man in his 40s was taken to hospital by paramedics from the West Midlands Ambulance Service and has since been released.
Police then travelled to a property on Flax Street and officers found the two children. Both children died at the scene.
Detectives renewed their appeal for any information and are particularly interested in any CCTV or dashcam footage from the area of Flax Street and Campbell Road between 1.30pm and 2.30pm on Sunday, and to hear from anyone in the area at the time.
Additional reporting by PA
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