Girl, 11, robbed at knifepoint on San Francisco sidewalk

File photo of police squad car at night. Patrol car with lights flashing File photo of police squad car at night. Patrol car with lights flashing Photo: Ron Chapple, Getty Image Photo: Ron Chapple, Getty Image Image 1 of / 1 Caption Close Girl, 11, robbed at knifepoint on San Francisco sidewalk 1 / 1 Back to Gallery

An 11-year-old girl waiting for her mother on a San Francisco sidewalk was robbed of her cell phone at knifepoint, police said Friday.

The mugging happened just after 7 p.m. Thursday at Persia Avenue and Paris Street in the Excelsior neighborhood, said Officer Robert Rueca, a police spokesman.

“She was alone on the sidewalk waiting for her mom who was nearby to come,” Rueca said of the young victim. “The suspect just saw this 11-year-old and decided to rob her.”

The assailant approached the girl from behind, held a knife against her back and demanded her phone, Rueca said. She immediately handed over the phone, and the robber ran off, he said.

The girl, whose name was not released, was not injured. No arrest was made and police did not release a detailed description of the robber.

Bill Hutchinson is a San Francisco Chronicle staff writer. Email: bhutchinson@sfchronicle.com Twitter: @Bill_Hutchinson