A Brooklyn man has been arrested in connection to a hammer attack in Union Square.

Jamar Newton, 41, allegedly got into an argument with a 44-year-old man at the Union Square subway station Saturday before attacking him, police say.

Police say Newton struck the victim in the back of the head with a hammer, causing him to fall onto the subway tracks.

The victim was taken to Bellevue Hospital and is expected to be OK.

Newton was arrested yesterday and is charged with assault, reckless endangerment and criminal possession of a weapon.