Two boys have died following an incident in Sheffield which has left four other children in hospital.
South Yorkshire Police said the teenagers, aged 13 and 14, died after they were taken to hospital on Friday morning.
This followed officers being called to property in Gregg House Road, in the Shiregreen area of the city, at around 7.30am.
Four other children, aged 11, 10 and three and one other aged seven months remain in hospital receiving treatment, a spokesman said.
Police have given no indication about the nature of the incident, but have said it was not a shooting.
A 37-year-old man and a 34-year-old woman have been arrested on suspicion of murder in connection with the incident, police said.
The Yorkshire Air Ambulance landed in the grounds of nearby Hartley Brook Primary Academy, but the incident is not thought to be related to the school.
The spokesman said that the boys' family have been informed and are receiving support from specially trained officers.
He said: "Cause of death has not yet been established and a post-mortem examination will be carried out in due course."
Detective Chief Inspector Simon Palmer said: "Detectives and specialist officers remain in the Gregg House Road area carrying out inquiries and we are working hard to ascertain the exact circumstances surrounding this incident.
"We will remain in the area this afternoon and into the evening carrying out inquiries and providing reassurance.
"I appreciate the events of this morning have caused concern locally, but I'd like to reassure you that there is no wider risk to the community.
"We will be providing regular updates when we are able to.
"If anyone does have concerns, please do not hesitate to speak to an officer in the area.
"To allow the investigation to progress, I would please ask that people are mindful of what they are posting on social media, and the potential distress this may cause."
The street was partially cordoned off as officers and forensics teams examined a semi-detached house.
The three-bedroom property is similar to many on the north Sheffield estate, but has an unkempt garden with an old, yellow Ford Fiesta parked on the front lawn, apparently abandoned.
Local resident Aaron Brunskill said neighbours came out into the street at about 8am to find around 15 police cars and four ambulances.
He said: "The police weren't telling us anything. I know there's children there. I've just seen them walking back to the shops and that's all I know."
Mr Brunskill added: "There were four ambulances. Everyone got took away in an ambulance. I don't know if the air ambulance was used."