A father was killed and his 15-year-old son was grazed by a bullet after they responded to an ad on Craigslist this weekend — a deadly robbery that ended Los Angeles’ 10-day streak of no homicides in the city, authorities said.

The father -- identified as Rene Balbuena -- was responding to a Craigslist ad with his son about 7 p.m. Saturday. Balbuena was there to buy a cellphone, according to authorities.

Investigators believe Balbuena and his son knocked on a door thinking they were meeting the party who posted the advertisement, but were told to go away.

The pair was sitting in a car at 92nd Street and Gramercy Place in South Los Angeles when two men -- believed to be those who posted the ad -- walked up and opened fire into the car, investigators said.

The 41-year-old father of two was shot three times in the upper torso and pronounced dead at a hospital. His 15-year-old son was treated at a hospital for a graze wound.

A neighbor who wished to remain anonymous because the gunmen are still at large told NBC4 she heard the shooting and ran outside to help.

"I said 911 was coming, they're on the way. He said, 'Please lady, tell me my daddy is going to be alright,'" she recalled.

The slaying happened just hours after the Los Angeles Police Department announced that there had not been a homicide in the city in 10 days and 10 nights – the longest streak since 2010.

Although the streak is over, the city homicide rate is still down 9 percent since last year, LAPD said.

“Homicides do happen,” LAPD spokesman Cleon Joseph said. “We’re happy we had a streak of this nature.”

No arrests have been made in this most recent killing, and the shooters are still at large.

"We're still talking to witnesses -- we just have a general description, right now," said LAPD detective Chris Barling.