A man has been arrested on suspicion of murdering a mother and her baby son in Birmingham.
The bodies of the 25-year-old woman and the nine-month-old boy were discovered at a house in Chells Grove, Billesley, at about 10:30 BST.
A 28-year-old man was arrested in Dudley at about 17:15 BST.
West Midlands Police said the man was known to the victims and officers were not looking for anyone else in connection with the deaths.
The force said it had referred the case to the Independent Police Complaints Commission due to "previous contact between police and the person in custody".
Chells Grove has been cordoned off while the scene is examined.
Supt Jo Chilton said: "This is a terrible crime and my thoughts are with the family of the victims who have been left devastated by today's events.
"We have a man in custody and are not looking for anyone else, but I am keen to speak to any witnesses or anyone who may have seen anything which could assist our investigation.
"Did you see anything suspicious in the area late Saturday night or early this morning? You may be able to help us and I would urge you to give us a call."