From KTLA.com:

New video has been released by detectives from LAPD's West Bureau Homicide Division, showing a passenger on transit bus seriously injured in a fight, in an effort to identify the suspect involved.

On the evening of April 5th, two passengers aboard a Santa Monica Big Blue Bus became involved in an argument that turned into a fistfight.

As a result of the fight, Luis Contreras suffered a serious head injury and is now fighting for his life at a local hospital. The bus was traveling in the area of Westwood Boulevard and Rochester Avenue in West Los Angeles when the incident occurred.