The collision that killed 30-year-old Andrew Zieman occurred on Wednesday around 7:55 a.m. near the corner of Franklin and Union streets, and involved multiple vehicles, according to police.
Officers found Zieman on the ground and despite live-saving measures by paramedics, he died at the scene. All vehicles involved stayed at the scene and cooperated with the investigation, police said.
Police determined the collision happened after a driver, identified as 70-year-old Susan Vennarucci, ran a red light. Officers arrested Vennarucci on suspicion of running a red light and vehicular manslaughter.
Impairment does not appear to be a factor in the case, police said.
Zieman was a paraeducator at Sherman Elementary School. In a letter to parents, Sherman Elementary School principal Helen Parker called Zieman a "beloved" longtime teacher who had also attended the school in his youth.
"We are struggling to understand this tragic loss of life, especially since he meant so much to so many students, families, and staff. Andrew taught from the heart. He was patient and kind, and always a positive role model. I am sure you will join me in offering our deepest condolences to his family and friends," Parker said in the letter.
The school is providing resources to students and school staff to help them deal with the sudden loss.
Zieman marks the 12th pedestrian to be killed in a traffic collision in the city this year.
Police are continuing to investigate the case and are asking anyone with information to call the Police Department's tip line at (415) 575-4444 or to send a tip by text message to TIP411 with "SFPD" at the start of the message.