A New York City Police Department rookie just couldn't wait to get started.

One of the NYPD's newest officers made his first arrest Thursday just minutes after graduating from the Police Academy in a ceremony at Madison Square Garden.

Officer Dariel Firpo, 23, was leaving the ceremony when he saw a 79-year-old man being robbed of his wallet by a mugger, police said.

The mugger tried to run, but Firpo caught him.

Firpo's feat "may be the fastest police action upon graduation in department history," said chief police spokesman Paul Browne, who was at the graduation ceremony for the class of 250 new officers.