Updated 07/03/11 – 1:28 p.m.

CHICAGO (CBS) — Bond was denied Sunday for a convicted sex offender charged with trying to kidnap a 2-year-old boy from North Avenue Beach.

Tyrone Hill, 37, has been charged with one count of attempted aggravated kidnapping of a child under 13 and one count of unlawful restraint, according to the Chicago Police Department.

Hill was arrested Saturday morning after he tried to abduct a 2-year-old boy near the boathouse at North Avenue Beach. But the boy’s father pulled his son to safety and police caught Hill before he was able to leave the beach.

As WBBM Newsradio 780’s Nancy Harty reports, Cook County Court Judge Maria Kuriakos Ciesel ordered Hill held without bond at a hearing Sunday afternoon.

Hill was convicted in 1997 of two counts of aggravated criminal sexual assault of a child, Cook County Assistant State’s Attorney William Hall said at Sunday’s hearing. Hill was 16 at the time and the victims were 7 years old.

LISTEN: Newsradio 780’s Nancy Harty Reports

Armando Uvalle, left, prevented a stranger Saturday from grabbing his 2-year-old son. (CBS)

Armando Uvalle says the attempted abduction of his 2-year-old son, Isaiah, happened in an instant while his son was next to him. It occurred on the east side of the boathouse.

A stranger “just came out of nowhere and grabbed my kid,” Uvalle told CBS 2’s Suzanne Le Mignot.

Uvalle pulled his son away and said the man walked away.

The father immediately went to a female officer from the 18th District at the beach and explained what happened.

The fast-acting officer immediately put a flash message out via police computer, alerting all officers nearby with the description of the suspect: an African-American man carrying several bags, wearing a black shirt with a white logo and black pants.

Two officers assigned to beach duty, from Area 3’s gang-enforcement unit, heard the alert on the radio. The officers saw the man matching the description at the North Avenue Beach turnaround.

Police arrested him.

“Don’t be afraid to get a hold of the police immediately,” Chicago Police Cmdr. Leo Schmitz told reporters at a news conference later Saturday. “If he didn’t do it that quickly, this guy might have gotten away and what if he got somebody else at another time.”

Uvalle said the whole process took seconds. His advice to other parents: “You got to be careful on the beach. People can just come right here and grab your kid.”