A woman who was struck and killed by a San Francisco Muni bus near Lake Merced on Saturday has been identified by the medical examiner's office as 72-year-old Eileen Barrett.

Barrett, a Daly City resident, was struck by an outbound 18-46th Avenue bus at about 4:30 p.m. at Lake Merced Boulevard and John Muir Drive, Muni spokesman Paul Rose said.

She was transported to a hospital with serious injuries, but it was initially thought she would survive, Rose said.

The bus operator will undergo drug and alcohol testing, as is standard protocol for such accidents, Rose said.

"While this incident is still under investigation, we offer our condolences to the family and friends of Ms. Barrett," Rose said. "Our top priority is the safety of those who utilize San Francisco streets, and we will work with authorities to find the cause of this accident in order to prevent it from happening again."