SANFORD -- George Zimmerman, granted a $150,000 bond, surprised a packed Central Florida courtroom Friday when he took the witness stand to tell Trayvon Martin’s parents he was sorry for the loss of their 17-year-old son.

Clean-shaven, handcuffed and wearing a charcoal suit, gray tie and shackles, the volunteer neighborhood watch captain faced Sybrina Fulton and Tracy Martin for the first time since he shot their son to death in a Feb. 26 encounter that set off a national debate about race, racial profiling and Florida’s controversial Stand Your Ground self-defense law.

“I am sorry for the loss of your son. I did not know how old he was,’’ he said, after taking the witness stand about two hours into the hearing. “I thought he was a little bit younger than I am. And I did not know if he was armed or not.”

As Zimmerman spoke in a soft, even voice, Trayvon’s parents, sitting in the second row, remained expressionless. Fulton, who had publicly asked for an apology, looked away.

When a prosecutor asked him why he had waited so long to express his condolences to the family of the Miami Gardens teen, he responded, “I was told not to communicate with them.”

Later, the family’s lawyer, Benjamin Crump, called the statement “a self-serving apology’’ designed to win Zimmerman release from jail until his trial on the second-degree murder charge.

At the conclusion of the hearing, Seminole County Circuit Court Judge Kenneth Lester Jr. granted the $150,000 bond — generally considered a reasonable amount by Florida standards — along with a set of restrictions for Zimmerman. Under the conditions, Zimmerman must wear an electronic tracking device, although he may be allowed to leave the state. He cannot have any contact with Trayvon’s family, carry firearms or consume alcohol or illegal drugs. He must abide by a curfew between 7 p.m. and 6 a.m. and check in with authorities every three days. He surrendered his passport at the beginning of Friday’s hearing.

Zimmerman’s attorney, Mark O’Mara, said it would be several days before his client, who is indigent, is released because Zimmerman needs time to come up with bail money. O’Mara also needs time to work out the details of the electronic tracking device. Zimmerman’s release date and location while he awaits the trial will remain secret because of threats made against him, O’Mara acknowledged.

Zimmerman, 28, fatally shot the teenager in a gated townhouse community in Sanford. Trayvon, who was on a 10-day suspension from his Miami-Dade high school, was spending time with his father and the father’s girlfriend at her home at the time of the shooting.

As Trayvon walked back to the home from a convenience store, Zimmerman spotted him. He told police the teen looked suspicious and followed him. Minutes later, they had a physical altercation and Zimmerman shot Trayvon. Zimmerman was not initially charged by Sanford police, who cited the state’s Stand Your Ground law. That lack of arrest fueled rallies and protests across the nation.

Charged last week, he faces a possible life sentence. Zimmerman has said he was acting in self-defense, a claim that may have been bolstered Friday when ABC News published what it said was an exclusive photo taken three minutes after Zimmerman shot Trayvon, showing the back of Zimmerman’s head with blood trickling down.