It happened around 2 p.m. near the intersection of Budlong Avenue and Martin Luther King Jr. Boulevard.
The brothers, who were identified by friends as 33-year-old Sergio Rios Jr. and his 19-year-old brother Ricardo Rios, were sitting inside a vehicle on Browning Boulevard when someone walked up and shot them, according to police.
One of the brothers died at the scene while the other died at the hospital. Police said it doesn't appear to be a random attack.
"We have an individual suspect, one lone suspect, that had a conversation with our two victims prior to the shooting," said LAPD Capt. Michael Lorenz. "Shortly thereafter, the suspect walks away, our victims go into the vehicle, the suspect walks up, fires rounds into the vehicle where both victims are struck by gunfire."
Family members were on the scene Saturday afternoon but were too distraught to speak. Sergio Rios Jr. was a father of twins. The family has created a GoFundMe to help the brothers' families, which has since raised more than $36,000.
Residents told ABC7 gunfire isn't unusual in the area but wish the violence would stop.
"Just think it's bad," said Jonathan Smith. "We've got a lot of kids out here, schools. If we could just lend a helping hand more than hating on each other ... it's a lot of hate going on."
Detectives don't believe the shooting is gang-related.
Meanwhile, the shooter remains at large. A detailed description wasn't available but police said the suspect was seen driving either a white Toyota or Lexus.
Anyone with information is urged to contact police.