DALY CITY -- An elderly woman struck by a Muni bus this weekend near Lake Merced has died from her injuries, a San Francisco Medical Examiner's office spokesman said Sunday.

The 72-year-old pedestrian was hit just before 4:30 p.m. Saturday by an outbound 18 46th Avenue bus near the intersection of John Muir and Lake Merced boulevards, said San Francisco Municipal Transportation Agency spokesman Paul Rose.

A preliminary investigation revealed the bus' middle half struck the senior as she walked in a crosswalk.

She was transported to San Francisco General Hospital and later pronounced dead, according to the coroner's office.

The victim's name has not been released pending notification of her next of kin, the coroner's spokesman said.

The cause of the crash remained under investigation Sunday and the Muni driver, who has been placed on leave, underwent standard drug and alcohol tests, Rose said.

Contact Natalie Neysa Alund at 510-293-2469. Follow her at Twitter.com/nataliealund.