The incident was reported near Riverside Drive and West 91st Street just after 6 p.m.
Three of the four people suffered injuries, but all were considered non-life-threatening, authorities said.
A 48-year-old female was hit in the head, a 55-year-old female suffered a minor head and hand injury and a 53-year-old male suffered a minor head injury.
All three victims were taken to an area hospital.
The Parks Department released a statement saying they will follow up with a full inspection of the tree to determine the cause of the limb failure.
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