The incident happened around 11:40 p.m. at a crosswalk on the corner of Santa Monica Boulevard and Palm Avenue. The bus was heading eastbound and the two men had just crossed the center median when they were hit.
Both victims were rushed to Cedars-Sinai Medical Center, where one later died.
Officials say the bus was not in service at the time of the accident, it was being moved from a bus yard to a West Hollywood facility. The bus was being driven by a maintenance worker, who MTA officials say was qualified to drive a bus.
Officials do not believe the driver was speeding. Authorities are downloading footage from the video camera on the bus, which will be used in the investigation.
Local residents say that section of Santa Monica Boulevard is always congested, and this crosswalk is not controlled by a traffic light and can be dangerous.
"A lot of people just aren't paying attention," said West Hollywood resident John Davis. "Even with a crosswalk like this that's heavily marked."
The MTA and the Los Angeles County Sheriff's Department are investigating. As part of the routine procedure, there will be a drug test and the driver will be placed on administrative leave until the investigation is finished.