A girl and a boy who died in a house in Stafford have been named by Staffordshire Police.
Meraj Ul Zahra, aged two, and Abdul Momin Alfaateh, three, were both found unresponsive with injuries inside a home in Corporation Street on Sunday morning, police said.
They both died at the scene.
Their next of kin have been informed and are being supported by specially trained officers.
A 43-year-old woman, from the Stafford area, who was arrested on suspicion of murder on Sunday, remains in custody while inquiries continue.
A police cordon also remains in place in Corporation Street.
The incident has been referred to the Independent Office for Police Conduct (IOPC) as is routine following earlier police contact, Staffordshire Police said.
Two ambulances and two paramedic officers were sent to the scene, West Midlands Ambulance Service said.
A spokesman said: "On arrival of ambulance staff we discovered two patients, both children.
"Sadly, it quickly became apparent nothing could be done to save them and they were confirmed dead at the scene."
Luke Browne, who lives in the street, said he saw a forensics van and a police car parked up as he left for work on Sunday morning.
The 61-year-old book shop owner said: "It's very sad. Children dying is a horror.
"It's quite painful to hear it."
Anyone with any information that could help with the investigation is asked to contact police on 101, or through the live chat facility on the police website, quoting incident number 147 of October 12.
To report information anonymously, Crimestoppers can be contacted on 0800 555 111.