The four teens were arrested May 13. District attorney's office spokeswoman Jane Robison said they were charged with murder, as adults.
The arrestees were identified as Christopher Santana, 19, Christopher Stratis, 17, Christine Alegre, 16, and Megali Fernandez, 17, according to a charge sheet from the district attorney's office posted on the San Gabriel Valley Tribune's Web site Wednesday.
A fifth suspect, 19-year-old Victor Maurtua III, an alleged member of the El Monte Flores gang, remained at large, said the Sheriff's Department.
Lt. Dan Rosenberg said Maurtua is known as "Lil Tiny," 5 foot 5 and weighs 140 pounds, the Los Angeles Times reported.
Hsiao Hsu, an immigrant from Taiwan who also goes by Michelle Hsu Hong and Michelle Chien, was shot by intruders in her sprawling home in March while she spoke on the phone to an emergency dispatcher. The dispatcher heard two shots, and authorities said Hsu was shot three more times as she was chased through her house.
The teens allegedly killed Hsu, a mother of two, to avoid arrest after they burgled her home, according to the charge sheet. If convicted, they face the death penalty.
The teens were being held without bail, and were scheduled to be arraigned on June 18, according to the charge sheet.
A woman reached by phone Wednesday night said she was related to Stratis but declined to comment. Attempts to find phone listings for the others were not successful.