Police arrested 31-year-old Matthew Juarez, a suspected gang member.
Candles now mark the spot on Shalimar Drive where the teen was stabbed on Saturday afternoon. She died at the hospital a few hours later.
Detectives are calling it a gang-related attack.
Costa Mesa police arrested Juarez at his home in Anaheim, with the assistance of the Anaheim Police Department.
Police said the victim's name is being withheld due to her age and the nature of the investigation.
The investigation into the deadly attack is ongoing. Detectives are asking anyone who may have information about the incident to contact Detective Peralta at 714-754-5039, or Investigator Molina at 714-754-5694.