A New Jersey mom taking pictures of her daughter at a gazebo in Central Park Friday was punched in the face without warning by a man who had walked up to her.

But a witness snapped pictures of him, too, sources said, and cops used them to track down the suspect, Robert Griner, 37, of Asbury Park, NJ, two hours later. He was charged with assault.

The attack on the woman, 36, happened 12:15 p.m. near 68th Street and Fifth Avenue. Police did not disclose the motive.