The stabbing between the suspect and victim - both homeless veterans - was reported at about 6:40 a.m. in the 11600 block of San Vicente Boulevard, according to the Los Angeles County Sheriff's Department.
Deputies found the victim with at least one stab wound and transported him to a hospital, where he was pronounced dead.
A preliminary investigation revealed the suspect was in a dispute with his girlfriend when the victim intervened and was stabbed, sheriff's officials said in a news release. The woman was not injured.
The suspect was detained at the scene by authorities and later taken to a hospital for medical clearance so he could be booked into jail, according to the sheriff's department. No weapon was retrieved from the scene.
4 hospitalized after car slams into homeless encampment on Koreatown sidewalk, LAFD says
Authorities stated the stabbing "solely involves the transient population surrounding the location."
The names of the suspect and victim have not been released.
"They were both my friends, and that's a difficult place to be," said GemBob Brookhyser, a homeless veteran. "I feel that yet again the VA has let down two veterans that had served their country."
L.A. City Attorney Mike Feuer, who is running for mayor, held a press conference outside the homeless encampment and called on the county to house the homeless veterans.
"It is time for there to be action. It is time for this encampment to end, for its residents to be housed, for the sidewalk to be clear," Feuer said.
He wants the encampment to be permanently removed from the street.
"This encampment is dangerous for its residents," he said. "It completely blocks the sidewalk in most places. No one should live this way."
City News Service contributed to this report