An 11-year-old boy died from stab wounds on Monday and his stepfather was detained as a "person of interest" in connection with the death, police said.
The incident happened about 9 a.m. in the 200 block of South Carondelet Street near MacArthur Park in the Westlake area, police said.
The 26-year-old stepfather, who police said suffered an injury to the shoulder, was taken into custody for questioning, Capt. Gary Walters, of the LAPD's Rampart Division.
A neighbor said she has called police before after hearing what she thought were a child's screams, "hitting sounds" and tears of agony coming from the second-floor apartment.
Another neighbor, who refused to be identified, said he heard a man inside the unit tell the boy to shut up or be quiet every week.
Police did not confirm the neighbors' accounts.