The police response to calls before the deaths of a toddler and a baby boy is being investigated by a watchdog.
The bodies of the three-month-old and the boy of three were discovered at a property in the Cheetham Hill area of Manchester just before 6pm yesterday.
Greater Manchester Police (GMP) has referred its handling of the investigation to the Independent Police Complaints Commission (IPCC).
A 21-year-old mother was being held today on suspicion of murdering her baby and toddler.
An IPCC spokesman: "We've had a referral and we're carrying out an assessment to see whether or not to investigate."
The spokesman said there were two different accounts from the police about contact with the family prior to the deaths.
He said: "We know there was some form of contact by the police. We need to determine what the police did in response to this contact. We're trying to get to the bottom of the police contact."
The IPCC spokesman explained the apparently "correct" account from the police about their contact with the family.
He said: "Police were contacted with 'expressions of concern' about the welfare of the woman.
"They went round to the property at about 2.50pm yesterday. They searched the area because a neighbour said she saw the woman walking away with her children.
"The next call they got was that the children were dead.
"We'll be asking what the police were told, what the concerns were, what the officers did, and decide whether there's anything there to take forward into an investigation."
A police spokesman outlined their response to "concern for welfare" reports at the house in Kilmington Drive.
He said police responded to a call yesterday afternoon by visiting the property, but did not enter it.
He said: "We went round to the house but there was no one there. We did checks with neighbours and area searches."
The police spokesman said the checks included a visit to a grandparent of the children, but there was no one there either.
He said: "While we were making these inquiries we got a 999 call which suggested that the children were back in the house, dead."
The spokesman was unable to confirm that the first phone call made to police was a 999 call.