A woman has been arrested on suspicion of murder after an 18-month-old baby fell from a sixth-floor window and died.
Police were called to Barkerend Road, Bradford, at about 17:10 BST on Saturday. Officers said it “quickly became apparent” the boy had died.
A 23-year-old woman arrested on suspicion of murder is receiving medical assessment in custody.
West Yorkshire Police said it was an “extremely traumatic incident”.
Det Supt Nick Wallen said: “Specially trained officers are working to support the child’s family members and those who witnessed what took place.
“It is no exaggeration to say those who witnessed this incident will have been deeply traumatised by what they saw.”
Police said they are not looking for anyone else in connection with the death.
A crime scene remains in place at the scene as inquiries continue.