A man has been arrested on suspicion of assault after a three-month-old boy was hit in the eye with a golf ball, police have said.
Officers were called to a playground in Birmingham on Friday evening by paramedics who attended the scene.
A spokeswoman for West Midlands Police said the incident happened outside Radley Court in Sheldon Heath Road at around 8.40pm.
"The three-month-old baby boy was taken to hospital with a serious eye injury, where he remains this morning," she said.
"A 36-year-old man was arrested on suspicion of assault and is currently in custody."
It is understood that the man and baby are not related.
The force said an investigation is under way and appealed for witnesses to come forward.