Residents heard gunfire and called 911. When officers arrived, they found the two victims on the sidewalk.
The LAPD says it has no suspects and no motive for the killings.
At a news conference announcing the reward Tuesday morning, Margarita Gutierrez, a relative of one of the victims, pleaded for anyone who knows something about the shootings to come forward.
"If anybody can help us find out who did this, please help us," said Gutierrez. "It isn't right. Until it hits you on your doorstep, you never know how it really feels. So please come forward and help."
Anyone with information is asked to call the LAPD at (877) 527-3247.