SAN DIEGO — A college student who was robbed when responding to a Craigslist ad was fatally shot by one of three teen assailants as he and his girlfriend followed them into a cul-de-sac, authorities said Thursday.

Officers found Garrett Berki, 18, of San Diego slumped behind the wheel of his car late Wednesday, said Lt. Kevin Rooney. He died less than an hour later at a nearby hospital from a single bullet wound.

"It does appear to have been a ruse robbery," Rooney said.

The 17-year-old suspects — Rashon Abernathy, Seandell Jones and Shaquille Jordan — were arrested on suspicion of robbery and murder after attempting to flee on foot.

They will be charged as adults Friday, said Steve Walker, a spokesman for the San Diego County district attorney's office. Prosecutors had not decided which charges to file, he said.

It wasn't immediately known if the three had attorneys.

Berki exchanged text messages with the alleged assailants to arrange the purchase in the gritty southeast San Diego neighborhood of Paradise Hills. Rooney declined to say what the item was, but said it had nothing to do with "drugs, prostitution or anything like that."

"It was a legitimate item," he said.

Berki drove with his 18-year-old girlfriend to meet the boys, who, after a brief conversation, robbed the couple of cash and cell phones, Rooney said. Berki pursued the Honda Accord on a freeway and eventually to a cul-de-sac in an effort to get a license plate.

The cars approached from opposite directions and — as they were almost side by side — one of the teens fired a single shot.

The suspects were caught about 15 minutes later, hiding in yards as police searched with a helicopter, Rooney said. They fled on foot after the car crashed in another cul-de-sac about two blocks from where the shooting occurred.

Berki lived with his mother in San Diego's seaside Pacific Beach area and attended community college. His parents went into seclusion after learning of his death, Rooney said.

Berki's girlfriend was uninjured.

The alleged attack is not the first Craigslist encounter to take a deadly turn.

In Tacoma, Wash., a 23-year-old man was sentenced to more than 100 years in prison last month for a killing related to the online shopping site. Prosecutors said Kioshi Higashi targeted a family for home invasion after the family advertised a diamond ring on Craigslist.

Two men were charged with murder in February in the killing of Hazel Park, Mich., man who was trying to buy a cell phone on Craigslist.

A medical student was accused of killing a New York City masseuse in April 2009 after meeting her on Craigslist. Philip Markoff killed himself as he awaited trial.

Rooney advised Craigslist users to meet in populated areas during the day.

"Whenever you're involved with Craigslist, keep in mind you're dealing with strangers," he said. "You don't know if they're good or bad."