NEW YORK – A New York 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 midtown Manhattan ceremony when he saw a 79-year-old man being robbed of his wallet and thrown to the ground by a mugger, police said.

The mugger tried to run away, but Firpo caught him without incident, they said.

"Officer Firpo made us all proud," police Commissioner Raymond Kelly said. "He's off to a great start."

The man Firpo arrested, Jeffrey Grant, was being charged with robbery. Grant, 47, has 48 previous arrests and was just released last week from Sing Sing Correctional Facility in Ossining, N.Y., after serving time for a robbery conviction, police said.

Grant, of Manhattan, was in custody late Thursday and couldn't be contacted. The name of his attorney wasn't yet on record.

The mugging victim was treated at a hospital for a broken wrist.

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.

Firpo, who graduated from Lehman College in January with a degree in political science, said he wants to focus on community affairs while working in the nation's biggest police department.

"I'm really trying to stick in the community," he said.