Family and friends of 18-year-old Garrett Berki gathered Thursday evening at Mission Beach near the home on the boardwalk that he shared with his parents and tried to understand how he wound up shot and killed the night before when a Craigslist deal turned into a robbery.

Three 17-year-old boys were arrested in connection with the killing of Berki, who was shot on a Paradise Hills street after he and his 18-year-old girlfriend pursued the thieves, San Diego police said.

Berki, a 2010 La Jolla High School graduate who was attending Mesa College, went with his girlfriend to Casey Street off Alta View Drive shortly before 10:30 p.m. Wednesday to buy an item that was advertised for sale on the Craigslist website, homicide Lt. Kevin Rooney said.

They were met in the southeastern San Diego neighborhood by three teens who pretended to be the sellers. "When they got there, there was a brief conversation and then one of the suspects produced a handgun and it became a robbery instead," Rooney said.

Police across the country, including locally, have documented cases where criminals used Craigslist ads to lure unsuspecting people and then rob them.

La Mesa police last year arrested two men who used Craigslist as part of a scam to rob two men of their iPad tablet computers. One of the men arrested pleaded guilty last week to grand theft. The other was ordered to stand trial.

In Wednesday's incident, a trio of thieves robbed the couple of cash and their cellphones, then drove away in a green Honda Accord, Rooney said.

Berki and his girlfriend followed the Honda to try to get its license plate number.

The Honda drove down Parkside Avenue and onto Artemia Way, a cul-de-sac. As the Honda driver turned around and passed the couple's car, someone in the Honda fired one shot, Rooney said. People in the area who heard the shot and the sound of a car speeding away called police, he said.

Officers found Berki, who was hit by one round, slumped behind the wheel of his car. He was taken to a hospital, where he died at 11:13 p.m., Rooney said.

The Honda turned onto Fleming Drive about two blocks away, where it jumped the curb and crashed at the end of the street. The driver and passengers got out and ran.

Minutes later, officers aided by a helicopter and search dogs found the three 17-year-old suspects hiding in backyards about a block away.

All three were booked into Juvenile Hall on suspicion of robbery and murder, Rooney said. He declined to say if investigators had determined which teen was the shooter or if the trio had any gang affiliations.

A spokeswoman with the District Attorney's Office said all three will be charged as adults. They were identified by the District Attorney's Office as Rashon Abernathy, Seandell Jones and Shaquille Jordan.

It is not clear if the teens planned the robbery and intended to lure a victim with the Craigslist ad or if they actually had something to sell, Rooney said.

He declined to say what was advertised for sale, but Alexander Berki, 23, said his brother was expecting to buy a computer.

"Garrett always had big dreams," his brother said in a phone interview from his home in New York City. "He wanted to be a businessman. If there was one word I would use to describe Garrett, it would be 'fearless.' He always wanted to go for it."

Alexander Berki said his brother was into cars and had just bought a 5-series BMW he "was really proud of."

"He loved to surf. He worked at In 'N Out Burger for maybe two years. He was always living life to the fullest. He wanted to try new things," his brother said.

About 100 people attended the vigil for Garrett Berki at Mission Beach, including his father, Edward; mother, Connie; and sister, Monica. His father described his son as "just a happy guy" who loved the ocean.

But, Edward Berki said, "When God calls you, you can't do anything. It was his time. It was his destiny."

He said the last time he saw his son was on Wednesday, and Garrett hugged his father and told him he loved him.

Edward Berki told the young people gathered at the beach to go home and "let your parents know how much you love them."